ライフサイエンスコーパス: sigmatropic

1 h cyclobutane ring cleavage to 12-annulenes, sigmatropic 1,5-H-shifts, electrocyclic ring-openings of

2 dearomative Al-C bond formation, subsequent sigmatropic [1,3]shifts, and a pericyclic reaction.

3 hylbenzo-2,3-diazafulvenium methides undergo sigmatropic [1,8]H shifts allowing the efficient synthes

4 Furthermore, the possibility of a [1,5] sigmatropic alkyl group shift of bicyclo[4.2.0]octa-2,4-

5 ll singlet biradical-mediated stepwise [1,5] sigmatropic alkyl group shift were shown to be comparabl

6 ficiently effected either by synfacial [3,3]-sigmatropic allylic imidate rearrangement or by direct,

7 cyclo[2.2.2]oct-2-ene (2) via a formal [1,3] sigmatropic carbon migration.

8 clobutene into biaryl occurs through a [1,3] sigmatropic carbon shift followed by [4+2] cycloextrusio

9 oes not govern stereochemistry for the [1,3] sigmatropic carbon shifts.

10 ic C-H oxidation, and a Myers' NBSH-promoted sigmatropic elimination to install the exo methylene gro

11 l or alkylidene groups to participate in the sigmatropic event.

12 azono)methyl)quinoxalin-2-ones, namely [3,3]-sigmatropic Fischer rearrangement with the formation of

13 drogen atom transfer (HAT) step, and a [1,5] sigmatropic H shift to regenerate the starting material

14 This reaction is a hybrid of a [1,2] sigmatropic hydrogen shift and a two-electron electrocyc

15 While the 1,5-sigmatropic hydrogen shift in cyclopentadiene is general

16 in D to vitamin D is an intramolecular [1,7]-sigmatropic hydrogen shift with antarafacial stereochemi

17 groups capable of participating in the [1,7]-sigmatropic hydrogen shift.

18 esponding allylic amines via Overman's [3,3]-sigmatropic imidate rearrangement, and subsequent one-po

19 an deuterium transposition consistent with a sigmatropic mechanism, and adding back silver salts resu

20 rting the predominance of a concerted [3, 3] sigmatropic mechanism.

21 rules are somewhat permissive for the [1,3] sigmatropic migration of carbon.

22 yield by a cascade mechanism that involves a sigmatropic migration, elimination, electrocyclization s

23 hat the transition structures of these [2,3]-sigmatropic migrations are aromatic.

24 The reaction can proceed via a sigmatropic or prototropic mechanism depending on the su

25 , the Banert cascade can proceed by either a sigmatropic or prototropic mechanism.

26 tion of which is a formal 10-electron double sigmatropic, or dyotropic, rearrangement.

27 monstrate that palladium(II)-catalyzed [3,3]-sigmatropic oxo-rearrangements can transform branched po

28 However, the stepwise sigmatropic pathway is suggested to only be feasible for

29 rences in barriers between electrocyclic and sigmatropic pathways.

30 lution counterpart, are thus concerted [3,3]-sigmatropic processes in which C-C bond formation lags b

31 derivatives indicate that both are concerted sigmatropic processes, controlled by the orientation of

32 quinone pK(a) values by plotting the percent sigmatropic products versus pH.

33 ith lower/higher free activation energies of sigmatropic/prototropic reactions, respectively.

34 e activity, suggests that MbtI may exploit a sigmatropic pyruvate elimination mechanism similar to th

35 nal work, the first example of a bifurcating sigmatropic reaction featuring a bispericyclic transitio

36 ted and 7-methoxy substituents favor the 1,5-sigmatropic reaction.

37 essentially pericyclic), the 11 --> 12 [3,3] sigmatropic rearrangement (pseudopericyclic), and simila

38 nic probe that selectively undergoes a [2,3]-sigmatropic rearrangement (seleno-Mislow-Evans rearrange

39 intramolecular transesterification and [1,5] sigmatropic rearrangement affords a series of helical co

40 featuring a Rh-mediated O-H insertion/[3,3]-sigmatropic rearrangement and subsequent alpha-ketol rea

41 nder the latter conditions resulted in [1,3]-sigmatropic rearrangement and subsequent oligomerization

42 Classic ACT transformations, including [3,3]-sigmatropic rearrangement and transition metal-catalyzed

43 functional theory (DFT) calculations of the sigmatropic rearrangement are in agreement with reactivi

44 s an additive increase the rate of the [3,3] sigmatropic rearrangement as well as the diastereoselect

45 The tandem ylide formation/[2,3]-sigmatropic rearrangement between donor/acceptor rhodium

46 Subsequent in situ enantioselective [2,3]-sigmatropic rearrangement catalyzed by the isothiourea b

47 diastereospecificity originates from a [3,3]-sigmatropic rearrangement followed by a sodium-assisted

48 nsient allenes by means of a strategic [2,3]-sigmatropic rearrangement followed by trapping of the re

49 e strategy is based on a [3,3]-allyl cyanate sigmatropic rearrangement from enantioenriched gamma-hyd

50 tero-Diels-Alder cycloadditions as well as a sigmatropic rearrangement have been located, and they al

51 hat rapidly undergoes either [3,3]- or [5,5]-sigmatropic rearrangement in one-pot to form a 2-amino-2

52 tion pathway provides rare examples of [2,3]-sigmatropic rearrangement in this class of compounds as

53 isomerization process that occurs via [3,3]-sigmatropic rearrangement induced by high oxidation stat

54 roduct is formed via an intramolecular [3,3]-sigmatropic rearrangement instead of the previously prop

55 ies on CaADH, while the exceptionally facile sigmatropic rearrangement is expected to drive computati

56 consistent with the observation that the 2,3-sigmatropic rearrangement is favored with donor/acceptor

57 A subsequent [3,3]-sigmatropic rearrangement is followed by intramolecular

58 ketyl radical-anion mechanism for the [3,3]-sigmatropic rearrangement is presented.

59 ions precedes a stereochemistry-determining sigmatropic rearrangement is reported.

60 hat the lowest energy pathway for each [3,5]-sigmatropic rearrangement is via an allowed, concerted p

61 N-Allyl enamines can undergo a [3,3] sigmatropic rearrangement known as a 3-aza-Cope (or amin

62 cond domino process, a [H]-shift and a [3,3]-sigmatropic rearrangement lead to the aromatization of t

63 tractive and highly diastereoselective [2,3]-sigmatropic rearrangement occurs when N-methyl-1,2,3,6-t

64 talin 55 is the oxyanionic-accelerated [3,3]-sigmatropic rearrangement of 37e.

65 heir alpha-position by an asynchronous [3,3]-sigmatropic rearrangement of a mixed acetal species whic

66 ds (78-89%) in a process involving the [1,4]-sigmatropic rearrangement of a nitrile-stabilized ammoni

67 dihydroxylation, and a stereoselective [2,3]-sigmatropic rearrangement of a selenoxide to effect a 1,

68 The base-induced [2,3]-sigmatropic rearrangement of a series of enantiopure 2-s

69 wn to be an effective catalyst for the [3,3]-sigmatropic rearrangement of a variety of substituted al

70 NEPHOS(AuCl)(2)), has been developed for the sigmatropic rearrangement of alkenyl-methylenecyclopropa

71 ve mechanisms of the gold(I)-catalyzed [3,3] sigmatropic rearrangement of allenyl vinyl ethers by den

72 development of an efficient oxidative [2,3]-sigmatropic rearrangement of allylic hydrazides, via sin

73 The [2,3]-sigmatropic rearrangement of allylic sulfoxides to allyl

74 Under certain conditions, the [2,3]-sigmatropic rearrangement of allyloxy carbonyl compounds

75 se of phase-transfer catalysis for the [2,3]-sigmatropic rearrangement of allyloxy carbonyl compounds

76 (II)-catalyzed oxonium ylide formation-[2,3] sigmatropic rearrangement of alpha-diazo-beta-ketoesters

77 abicyclo[5.3.0]decane ring system by a [3,3] sigmatropic rearrangement of an acylimmonium ion followe

78 rbocyclic core of these targets were a [2,3]-sigmatropic rearrangement of an allylic sulfur ylide to

79 conocene-promoted ring contraction and [3,3] sigmatropic rearrangement of an enynol.

80 eveloped via a dichlorocarbene insertion and sigmatropic rearrangement of an in situ generated ylide.

81 We find the barrier for sigmatropic rearrangement of chemisorbed hydrogen atoms

82 ence for a mechanism that involves the [3,3] sigmatropic rearrangement of divinylcyclopropanes.

83 he scope of the NCS-mediated amination/[2,3]-sigmatropic rearrangement of enantioenriched allylic sel

84 ed to the allylic amines via Overman's [3,3]-sigmatropic rearrangement of imidates.

85 systems are prepared by acid-catalyzed [3,3]-sigmatropic rearrangement of O-aryloximes.

86 nsformed directly to allenes through a [2,3]-sigmatropic rearrangement of propargyl phosphites.

87 mparative study of the Au(I)-catalyzed [3,3]-sigmatropic rearrangement of propargylic esters and prop

88 Sigmatropic rearrangement of spirocyclic pyrazoles to fu

89 Herein, we describe a gold-catalyzed sigmatropic rearrangement of sulfonium and selenium ylid

90 cationic gold(I)-catalyzed asymmetric [3,3]-sigmatropic rearrangement of sulfonium leads after cycli

91 er-catalyzed generation and subsequent [2,3]-sigmatropic rearrangement of sulfur ylides is strongly d

92 resolution is enabled by a spontaneous [3,3]-sigmatropic rearrangement of the allylic azide.

93 Products are obtained by [3,3]-sigmatropic rearrangement of the azasulfonium enolate or

94 The process involves a [3,3] sigmatropic rearrangement of the in situ generated mixed

95 Instead, a [3,3]-sigmatropic rearrangement of the initial cyclization int

96 ith the N-Boc-oxaziridine 1 results in [2,3]-sigmatropic rearrangement of the intermediate allylic N-

97 Quantum chemical calculations of a [3,3]sigmatropic rearrangement of the N,O-divinyl hydroxylami

98 rs at the terminal oxygen, followed by [2,3]-sigmatropic rearrangement of the pendant allyl group, in

99 The mechanism involves a [2,3]-sigmatropic rearrangement of the respective selenoxides

100 bsolute stereochemistry and (ii) a new [3,3]-sigmatropic rearrangement of the thiono-Claisen variety

101 The title [3,3] sigmatropic rearrangement proceeds in generally excellen

102 The 2,3-sigmatropic rearrangement proceeds through initial cleav

103 reochemically unscathed by competitive [3,3]-sigmatropic rearrangement processes.

104 C gives a modest yield of the initial [3,5]-sigmatropic rearrangement product, 2,6-diacetoxy-6-methy

105 refore affords the radical anion without any sigmatropic rearrangement products.

106 he semiquinone which is rapidly converted to sigmatropic rearrangement products.

107 The first example of a biocatalytic [2,3]-sigmatropic rearrangement reaction involving allylic sul

108 s-alkenes is evidenced by their formal [1,3]-sigmatropic rearrangement reactions and the rapid additi

109 Furthermore, we report on the limitations of sigmatropic rearrangement reactions of aryl allyl anilin

110 s via stereocontrolled cyanate-to-isocyanate sigmatropic rearrangement reactions of the corresponding

111 rgo thermal and photolytic cycloaddition/1,5-sigmatropic rearrangement reactions with 11a-d with N(2)

112 engineered to initiate a sulfimidation/[2,3]-sigmatropic rearrangement sequence in whole E. coli cell

113 rignard ring opening/allylic sulfoxide [2,3]-sigmatropic rearrangement sequence previously developed

114 anistic insight hinges on a reversible [3,3]-sigmatropic rearrangement step, supported by (1)H NMR st

115 f kinetic resolution, and the stereospecific sigmatropic rearrangement step, which proceeds with full

116 A dearomative [3,3']-sigmatropic rearrangement that converts N-alkenylbenziso

117 cyclo[4.2.0]oct-2-ene (1a) undergoes a [1,3] sigmatropic rearrangement to 5-exo- and 5-endo-methoxybi

118 cyclo[4.2.0]oct-2-ene (1a) undergoes a [1,3] sigmatropic rearrangement to 5-methylbicyclo[2.2.2]oct-2

119 binaphthyl hydrazines undergo a facile [3,3]-sigmatropic rearrangement to afford enantiomerically enr

120 lowed by an orthoester Johnson-Claisen [3,3]-sigmatropic rearrangement to construct a sterically dema

121 active intermediate undergoes a pseudo-[1,4]-sigmatropic rearrangement to directly furnish heterocycl

122 The route relies on the aza-[2,3]-Wittig sigmatropic rearrangement to efficiently install the rel

123 ee major thermal rearrangements, namely, 3,3-sigmatropic rearrangement to form 1,2,3-triazine (2), al

124 incipally via SO2-N bond homolysis and [1,5] sigmatropic rearrangement to generate 37, 10 proceeded v

125 ive trans-1,3-pentadiene, 40 +/- 3% of [3,3]-sigmatropic rearrangement to give cis-3-penten-2-yl acet

126 give cis-1,3-pentadiene, 32 +/- 2% of [3,3]-sigmatropic rearrangement to give trans-3-penten-2-yl ac

127 lled stereoselective Mislow-Evans-type [2,3]-sigmatropic rearrangement to install the C5 stereocenter

128 ting ISDA cycloadduct either undergoes [3,3]-sigmatropic rearrangement to the more stable major IHDA

129 cycloaddition participate in a thermal [3,3] sigmatropic rearrangement to yield bicyclo[3.3.2]decadie

130 The most favored [3,3]-sigmatropic rearrangement transition state is bimodal, l

131 Several [3,3] sigmatropic rearrangement transition states were also lo

132 ged 16-acetate (2), which can form from 1 by sigmatropic rearrangement under basic conditions, batrac

133 sors are readily prepared and undergo smooth sigmatropic rearrangement upon exposure to iodosobenzene

134 n demonstrated by combining the Mislow [2,3]-sigmatropic rearrangement with catalytic asymmetric hydr

135 These systems undergo the [3,3] sigmatropic rearrangement with high selectivity, with a

136 lowed by a probable 1,3-OAc migration ([3,3]-sigmatropic rearrangement).

137 om an unexpected and remarkably facile [1,3]-sigmatropic rearrangement, and a tactic to disfavor the

138 via a gold-catalyzed tautomerization, [3,3]-sigmatropic rearrangement, and cyclodehydration process.

139 ocyclization of the hexatriene system, [1,9]-sigmatropic rearrangement, and heterocyclic ring opening

140 as the tandem cyclization followed by [2,3]-sigmatropic rearrangement, as well as cyclization of the

141 cyclopropenation, sulfur ylide formation/2,3-sigmatropic rearrangement, as well as nitrogen ylide for

142 cluding [2 + 2] photocycloaddition and [3,3] sigmatropic rearrangement, indicating the possibility fo

143 zomethine ylides, [3 + 2]-cycloaddition, 1,3-sigmatropic rearrangement, Michael addition, and Pictet-

144 rhodium-bound oxonium ylide formation, [2,3]-sigmatropic rearrangement, oxy-Cope rearrangement, enol-

145 on to N-fused pyrroles proceeded via a [3,3]-sigmatropic rearrangement, the analogous cycloisomerizat

146 The disfavored [3,3]-sigmatropic rearrangement, which would produce the unobs

147 rmed through the use of a Still-Wittig [2,3]-sigmatropic rearrangement, while the trans mimic, the (E

148 gold catalyzed enantioselective tandem [3,3]-sigmatropic rearrangement-[2+2]-cyclization.

149 ion forms by a hemiketal-oxy-Cope type [3,3]-sigmatropic rearrangement-intramolecular aldol condensat

150 ilable tartrate derivative were obtained via sigmatropic rearrangement.

151 s formed immediately after the initial [3,3] sigmatropic rearrangement.

152 of oxonium ylide formation followed by [2,3]-sigmatropic rearrangement.

153 ations is combined with a diastereoselective sigmatropic rearrangement.

154 alpha-chloro sulfide intermediates and [2,3] sigmatropic rearrangement.

155 oxonium ylide formation followed by a [2,3]-sigmatropic rearrangement.

156 described as a concerted asynchronous [3,3]-sigmatropic rearrangement.

157 rmediate and facilitates the rate of the 3,3-sigmatropic rearrangement.

158 4 + 2) cyclohexenyl products through a [3,3]-sigmatropic rearrangement.

159 dolines via a thionium ylide-initiated [3,3]-sigmatropic rearrangement.

160 through the use of an Ireland-Claisen [3,3]-sigmatropic rearrangement.

161 e expected indane by an unusually facile 1,3-sigmatropic rearrangement.

162 commodity materials via the Ireland-Claisen sigmatropic rearrangement.

163 aza-arene N-oxides, triggering a rapid [3,3]-sigmatropic rearrangement.

164 athway alongside the thermally allowed [2,3]-sigmatropic rearrangement.

165 ycloaddition and N-alkenylisoxazoline [3,3']-sigmatropic rearrangement.

166 C-N bond formation, deprotonation, and a 3,3-sigmatropic rearrangement.

167 mixed acetal formation and subsequent [3,3] sigmatropic rearrangement.

168 a mixture of regioisomers upon heating via a sigmatropic rearrangement.

169 nverted to 3-hydroxy tetrahydropyridines via sigmatropic rearrangement.

170 luorescent indicator based on the 2-aza-Cope sigmatropic rearrangement.

171 pansion of the anionic intermediate by [1,3] sigmatropic rearrangement.

172 ate of hydrogenation relative to the rate of sigmatropic rearrangement.

173 titution via suprafacial allylic azide [3,3]-sigmatropic rearrangement.

174 d promotes its evolution to HCTD via a [1,2]-sigmatropic rearrangement.

175 e species becomes competitive with the [3,3]-sigmatropic rearrangement.

176 The reaction proceeds via [3,3]-sigmatropic rearrangement/5-exo-dig cyclization of N-pro

177 (+)-latifoline (1) employing a tandem [3,3] sigmatropic rearrangement/[1,2] allyl shift as a key ste

178 rough an interrupted Pummerer reaction/[3,3]-sigmatropic rearrangement/cyclization sequence to delive

179 lines efficiently from silver-mediated [3,3]-sigmatropic rearrangement/Diels-Alder reaction of 1,9-di

180 of a stereoselective one-pot oxidative [3,3] sigmatropic rearrangement/Friedel-Crafts arylation that

181 KOtBu-induced E2 elimination, undergo [3,3]-sigmatropic rearrangement/intramolecular 5-exo-dig cycli

182 ey step in the synthesis, a sequential [2,3]-sigmatropic rearrangement/syn-elimination of an allyl su

183 gement (pseudopericyclic), and similar [3,3] sigmatropic rearrangements (all pericyclic), and detaile

184 [2,3]-Sigmatropic rearrangements (Wittig rearrangements) of al

185 Sigmatropic rearrangements are an important fundamental

186 0(2,8)]tridec-10-ene (13TCT) undergoes [1,3] sigmatropic rearrangements at 315 degrees C in the gas p

187 [3,3]-Sigmatropic rearrangements have been widely utilized for

188 rong experimental evidence that direct [3,5]-sigmatropic rearrangements in these molecules are favore

189 Results of calculations on the [3,3] sigmatropic rearrangements involving additional transiti

190 promote thermodynamically unfavorable [3,3] sigmatropic rearrangements of 3,3-dicyano-1,5-dienes to

191 Earlier studies have shown that [3,3]-sigmatropic rearrangements of allyl esters are useful fo

192 The [2,3]- and [1,2]-sigmatropic rearrangements of ammonium ylides are studie

193 [2,3]-Sigmatropic rearrangements of beta-unsaturated sulfinyl

194 l computational study of the concerted [3,3] sigmatropic rearrangements of cis-1-iminyl-2-ketenylcycl

195 ta- and delta-eliminations, as well as [3,3]-sigmatropic rearrangements of esters are primarily pseud

196 rroles has been achieved via [3,3] and [1,3] sigmatropic rearrangements of O-vinyl oximes, respective

197 relative rate constants for ring opening and sigmatropic rearrangements of the dihydrophenanthrene in

198 of dynamic trajectories in [1,2]- and [2,3]-sigmatropic rearrangements suggests a counterintuitive a

199 ns, ranging from cycloaddition reactions and sigmatropic rearrangements to C-H functionalizations, th

200 The carbene undergoes two [1,2]-sigmatropic rearrangements via competing 1,2-C atom shif

201 Three sigmatropic rearrangements were employed in building the

202 esting and unexpected [1,2]-Wittig and [1,3]-sigmatropic rearrangements were identified during the op

203 no-Claisen variety that is among the fastest sigmatropic rearrangements yet reported.

204 arrangements, as well as some typical [2, 3]-sigmatropic rearrangements, e.g., thermal rearrangements

205 It is based on two subsequent [3,3]-sigmatropic rearrangements, in particular, Johnson-Clais

206 e failed, we uncovered another set of tandem sigmatropic rearrangements, leading to vinyl imidate for

207 Here, using a series of sequential [3,3]-sigmatropic rearrangements, we report the total synthesi

208 Sigmatropic rearrangements, while rare in biology, offer

209 ry expected for classically pericyclic [3,3] sigmatropic rearrangements.

210 les are favored over the more familiar [3,3]-sigmatropic rearrangements.

211 t center and easily undergoes an endocyclic, sigmatropic ring-closing reaction to form the final 2H-c

212 ntal assays refute a plausible concerted 1,3-sigmatropic S- to N-rearrangement of MTSB that would lea

213 6pi-electrocyclization (2 --> 3) and [1,5]H-sigmatropic shift (2 --> 4), among which the activation

214 -allyl-6-iminotriazocine 30 to 32, the [3,3]-sigmatropic shift (aza-Cope rearrangement) is preferred

215 ese adducts can interconvert through a [3,3] sigmatropic shift (Cope rearrangement).

216 ition, 6 thermally rearranges to 7 via a 1,5-sigmatropic shift (DeltaG(267K) = 20.0 +/- 0.5 kcal/mol)

217 on (i) of configuration dominates this [1,3] sigmatropic shift although some retention (r) is also ob

218 The new Ir(III) complex photocatalyzes a sigmatropic shift and [2 + 2] cycloaddition reactions th

219 of a fluorine atom at C3 also interrupts the sigmatropic shift and changes the rate-determining step

220 ns in which two cycloadducts are linked by a sigmatropic shift have been identified.

221 The [3s,5s]-sigmatropic shift is an example of an orbital-symmetry f

222 obvious similarities to the well-known [3,3]-sigmatropic shift of 1,5-hexadiene, i.e., the Cope rearr

223 p-substituents, may arise from 5 by a [1,3]-sigmatropic shift of chlorine proceeding via polar trans

224 pha-ketophosphonates are prepared by a [3,3]-sigmatropic shift of enolphosphonates.

225 n, a 6pi electrocyclic ring closure, a [1,5]-sigmatropic shift of hydrogen, a 6pi electrocyclic ring-

226 ype of electrocyclic reaction known as a 1,5-sigmatropic shift of hydrogen.

227 arrangement of quinazoline 5 to 9, the [1,3]-sigmatropic shift of the thioamido group with an activat

228 n electron-rich 7-substituent favors the 1,5-sigmatropic shift reaction.

229 rmed due to the tandem 6n-electrocyclization/sigmatropic shift reaction.

230 etro-ene type [2pi + 2pi + 2sigma] and [3,3]-sigmatropic shift reactions involving the substituent gr

231 Suprafacial sigmatropic shift reactions of 5-substituted cyclopentad

232 is proposed to involve E2, S(N)2', and [2,3]-sigmatropic shift reactions.

233 th nucleophile trapping (alkylation) and 1,5-sigmatropic shift reactions.

234 shell processes-concerted cycloadditions and sigmatropic shift rearrangements of cycloadducts.

235 inimum, leading to a switch from a concerted sigmatropic shift to its aborted or interrupted versions

236 e for an unexpected oxyanion-accelerated 1,2-sigmatropic shift was also found for certain systems, le

237 methodology to a sequence involving a [1,3] sigmatropic shift was feasible with a cyclopropylmethyl

238 C into the first example of an aborted [3,3] sigmatropic shift where the pericyclic "transition state

239 conditions are reported that effect a [3,3]-sigmatropic shift whose two-step process is interrogated

240 ike 21 23 can take place by means of a [1,3]-sigmatropic shift with a low barrier ( 17.5 kcal/mol) ra

241 compound 8 undergoes a very fast 1,3-lithium sigmatropic shift, and all of the phenyls in the above c

242 ant, although other processes, including the sigmatropic shift, are not excluded.

243 hat it functions as a substituent on a [3,3] sigmatropic shift, rather than a nucleophile; thus, the

244 p from the conformation required for the 1,5-sigmatropic shift, then nucleophile trapping occurs.

245 position is therefore favored in the initial sigmatropic shift.

246 om to which it migrates in the result of the sigmatropic shift.

247 deprotonation reaction, thereby limiting the sigmatropic shift.

248 n that is outcompeted by the allowed [3s,3s]-sigmatropic shift.

249 goes a skeletal reorganization through a 1,3-sigmatropic shift/retro-Mannich reaction with the net fo

250 [3,3]-Sigmatropic shifts (hetero-Cope rearrangements) of the c

251 Competing [4 + 2] cycloadditions and various sigmatropic shifts are also explored.

252 The [1,3] carbon sigmatropic shifts are not controlled by orbital symmetr

253 details of stereomutations and [1,3] carbon sigmatropic shifts are now being pursued and will in tim

254 experiments revealed that sulfur can undergo sigmatropic shifts around all four sides of the diazetin

255 connection between anionic cyclizations and sigmatropic shifts offers new possibilities for the desi

256 The thermal stereomutations and [1,3] carbon sigmatropic shifts shown by (+)-(1S,2S)-trans-1-(E)-prop

257 Compounds 5 and 8 undergo fast 1,3-Li-sigmatropic shifts that are proposed to take place withi

258 rconversions of various cycloadducts through sigmatropic shifts were also explored.

259 ts for electrocyclic ring closures and [3,3] sigmatropic shifts, processes dominated by heavy-atom mo

260 range via stepwise [1,3]- or concerted [3,3]-sigmatropic shifts, ultimately converging to provide the

261 ions can be considered to be "aborted" [2,3]-sigmatropic shifts.

262 migration occurs through a series of formal sigmatropic shifts.

263 effectively with concerted symmetry-allowed sigmatropic steps, and (3) azolium methanide zwitterions

264 mics and the activation barrier of the [3,3]-sigmatropic tautomerism.

265 to functionalized allenes through the [3,3]-sigmatropic transformation of propargyl vinyl ethers.

266 rgies, and electronic characteristics of the sigmatropic transposition compared to those of the unsub