ライフサイエンスコーパス: pericyclic

1 ement over whether it is pseudopericyclic or pericyclic.

2 terion for determining whether reactions are pericyclic.

3 , if any, are pseudopericyclic as opposed to pericyclic.

4 e 13 --> 14 and 15 --> 16 rearrangements are pericyclic.

5 oat-shaped geometry expected for classically pericyclic [3,3] sigmatropic rearrangements.

6 monstrate a group of enzymes that catalyse a pericyclic [6+4] cycloaddition, which is a crucial step

7 compared with closed-shell reactions such as pericyclic additions.

8 A clear differentiation between a purely pericyclic and a purely pseudopericyclic mechanism is es

9 l selectivities compared to more traditional pericyclic and carbocation-based rearrangements.

10 The relative positions of the bis-pericyclic and Claisen rearrangement transition states m

11 t the line between the recently proposed bis-pericyclic and Diels-Alder routes is blurred, and favora

12 It is further argued that when both pericyclic and pseudopericyclic orbital topologies are a

13 emipseudopericyclic" (halfway between purely pericyclic and purely pseudopericyclic).

14 onclusions that the 5 --> 6 rearrangement is pericyclic and that the 15 --> 16 rearrangement is pseud

15 imilar [3,3] sigmatropic rearrangements (all pericyclic), and detailed rationales for these latest re

16 those involving nucleophilic, electrophilic, pericyclic, and radical reactions.

17 beta-eliminations have been suggested to be pericyclic, B3LYP/6-31G(d,p), MP2 and MP4 calculations s

18 We expect that more pericyclic biosynthetic enzymatic transformations remain

19 e initial benzannulation step proceeds via a pericyclic cascade mechanism triggered by thermal or pho

20 rall transformation proceeds via a two-stage pericyclic cascade mechanism.

21 e derivatives are described that proceed via pericyclic cascade mechanisms featuring the participatio

22 dehydes has led to accidental discoveries of pericyclic cascade reactions that produce Z-alpha,beta-u

23 elta-unsaturated amides, a thermally induced pericyclic cascade rearrangement that converts Zincke al

24 an ynamide derivative in the first step of a pericyclic cascade that produces a highly substituted an

25 The success of this pericyclic cascade was critically dependent on the subst

26 lectrocyclic ring-opening/hetero-Diels-Alder pericyclic cascade.

27 anation of the range of pseudopericyclic and pericyclic characters found in related reactions.

28 have been unified at one time by underlying pericyclic chemistry.

29 yclic geometries are argued to reflect small pericyclic contributions.

30 On the potential energy surface, the bis-pericyclic cycloaddition transition state is followed by

31 The reactions include pericyclic, cycloaromatization, radical cyclization and

32 t in the cells surrounding primary xylem and pericyclic fibers in N. sylvestris.

33 The mechanisms of a variety of thermal pericyclic fragmentation reactions of five-membered hete

34 However, the structure of the pericyclic geometry has yet to be observed experimentall

35 o form a superelectrophile able to promote a pericyclic group transfer reaction with allyl alcohols.

36 lied to natural product synthesis, including pericyclic, heteroatom-mediated, cationic, metal-catalyz

37 ion states resulting in a web of products by pericyclic interconversion pathways.

38 the last five years are discussed, including pericyclic, ionic, metal-catalyzed, organocatalytic, and

39 er)(CBS-QB3(0K)) = 19.0 kcal/mol) is not bis-pericyclic, leading to nondegenerate primary and seconda

40 4]-cycloaddition proceeding in a completely pericyclic manner.

41 ett principle, however, reveals that the bis-pericyclic mechanism accounts for approximately 83% of t

42 that, by using suitable functional groups, a pericyclic mechanism can be converted into a pseudoperic

43 transition state for thermal reactions and a pericyclic minimum in the excited state for photochemica

44 The structural motion into the pericyclic minimum is dominated by rehybridization of tw

45 re-to-valence spectroscopic signature of the pericyclic minimum observed in the experiment was charac

46 ons to image structural dynamics through the pericyclic minimum of a photochemical electrocyclic ring

47 y happens after internal conversion from the pericyclic minimum to the electronic ground state.

48 mediate excited-state minimum (the so-called pericyclic minimum), which leads to isomerization via no

49 Moreover, the pericyclic nature of the electrocyclizations was confirm

50 d hence the process is likely neither purely pericyclic nor pseudopericyclic.

51 ns of conjugated allenes or ketenes follow a pericyclic or a pseudopericyclic mechanism has triggered

52 reaction pathways involving either nonpolar pericyclic or bifurcating ambimodal cycloadditions.

53 Aborting the pericyclic path facilitates trapping of cyclic intermedi

54 emplated electrocyclic ring-opening, but the pericyclic pathway is predicted to dominate for more ela

55 nyl)triazenes is proposed to occur through a pericyclic pathway.

56 fects establish a concerted but asynchronous pericyclic pathway.

57 ompetition between concerted and interrupted pericyclic pathways can be finely tuned via a combinatio

58 ght into the factors influencing the various pericyclic pathways operative in this system.

59 The ene reaction is a pericyclic process in which an alkene with an allylic hy

60 However, this reaction is not a pericyclic process; the stereoselectivity is probably of

61 s of nitroalkenes is described in which both pericyclic processes are intramolecular.

62 hese results are compared to other forbidden pericyclic processes driven by steric constraints and st

63 eaction profile; however, the use of BCBs in pericyclic processes has to date been largely overlooked

64 yclopropanes participate in polar reactions, pericyclic processes, radical-based reactions, and C-C b

65 ategy is described based on a cascade of two pericyclic processes.

66 ps can be formulated as oxyanion-accelerated pericyclic processes.

67 1,3,5-hexatriene is a textbook example of a pericyclic reaction and has been amply investigated with

68 The reaction proceeds by way of a pericyclic reaction cascade and leads to the formation o

69 Their participation in pericyclic reaction cascades, leading to sp(3)-rich poly

70 3 with a rate approaching that of a related pericyclic reaction catalysed by the enzyme chorismate m

71 This nonenzymatic pericyclic reaction is considered to be biomimetic.

72 Enzymatic systems that exploit pericyclic reaction mechanisms are rare.

73 structure representations, in tautomers and pericyclic reaction partners in which only one compound

74 S) that leads to formation of four different pericyclic reaction products ([4 + 6]-, [2 + 8]-, [8 + 2

75 The Nazarov cyclization is an important pericyclic reaction that allows the synthesis of substit

76 that catalyses an oxy-Cope rearrangement, a pericyclic reaction that belongs to a well studied and w

77 an example of an orbital-symmetry forbidden pericyclic reaction that is outcompeted by the allowed [

78 re suggests that the antibody catalyzes this pericyclic reaction through a combination of packing and

79 We contrast here examples of pericyclic reaction transition structures (where aromati

80 The combination of this pericyclic reaction with a catalytic metathesis reaction

81 dienes which will be involved in the second pericyclic reaction with juglone to construct the tetrac

82 rate Cope rearrangement of semibullvalene, a pericyclic reaction, is used as an example to visually i

83 stic studies support a domino hydroamination/pericyclic reaction, which includes the formation of the

84 ne is generally thought to be a unimolecular pericyclic reaction, Yamabe proposed a more complex bimo

85 nto substituent effects of this prototype of pericyclic reaction.

86 n, subsequent sigmatropic [1,3]shifts, and a pericyclic reaction.

87 byU active site to facilitate a transannular pericyclic reaction.

88 nter were asymmetrically synthesized using a pericyclic-reaction cascade and obtained in a high ee of

89 nificant) with those for illustrative pseudo-pericyclic reactions (where aromaticity is less or not i

90 dily react with nucleophiles, participate in pericyclic reactions and activate inert sigma-bonds.

91 cade process proceeds via a sequence of four pericyclic reactions and furnishes a multiply substitute

92 ard-Hoffmann rules predict whether concerted pericyclic reactions are allowed or forbidden based on t

93 Pericyclic reactions are powerful transformations for th

94 e lines of a biosynthetic proposal involving pericyclic reactions as key steps.

95 tions supported the possibility of transient pericyclic reactions as part of the isomerization-signal

96 Pericyclic reactions bypass high-energy reactive interme

97 ules that can be formed within four polar or pericyclic reactions from water and hydrogen cyanide (HC

98 Most characterized enzymatic pericyclic reactions have been cycloadditions, and it ha

99 ported examples of transition metal-mediated pericyclic reactions have been shown to proceed by nonpe

100 Pseudomonas aeruginosa (PchB) catalyzes two pericyclic reactions in a single active site.

101 aerugionsa (PchB) achieves catalysis of both pericyclic reactions in part by the stabilization of rea

102 The prevalence of potential metal-supported pericyclic reactions in this system suggests that one sh

103 Despite the prominence of pericyclic reactions in total synthesis, only three natu

104 The rules for allowable pericyclic reactions indicate that the photoisomerizatio

105 our heteroatoms dance in the cascade of four pericyclic reactions initiated by ozonolysis of C=N bond

106 s how enzymes are able to catalyse concerted pericyclic reactions involving ambimodal transition stat

107 molecular basis of catalysis among enzymatic pericyclic reactions is a matter of debate, one view hol

108 mation and bond breaking that is typical for pericyclic reactions is lost in their mechanistic cousin

109 c Umpolung, in which the regioselectivity of pericyclic reactions is reversed relative to the predict

110 d, the highly organized, concerted nature of pericyclic reactions makes inverting their conventional

111 Non-pericyclic reactions may also have aromatic transition s

112 Knoevenagel chemistry and pericyclic reactions meet again to expand the polyene-ca

113 Four sequential pericyclic reactions occur, namely two Diels-Alder/retro

114 lk rearrangements of BCP, BCN, and DCBCN are pericyclic reactions occurring with a strong preference

115 Ten representative pericyclic reactions that showcase the development and e

116 d ynamides proceeds via a cascade of several pericyclic reactions to generate multiply substituted an

117 with ynamides proceeds via a cascade of four pericyclic reactions to produce multiply substituted ani

118 The conceptual dehydrogenation of pericyclic reactions yields dehydropericyclic processes,

119 ricyclases-a family of enzymes that catalyse pericyclic reactions(1).

120 periselectivity (selectivity among possible pericyclic reactions).

121 Similar to pericyclic reactions, an electron count can be used to p

122 romophores, have proven useful in a range of pericyclic reactions, bond dissociations, and isomerizat

123 Pseudomonas aeruginosa (PchB) catalyzes two pericyclic reactions, demonstrating the eponymous activi

124 a-c into [8]AGNR occurs via a series of Hopf pericyclic reactions, followed by aromatization reaction

125 Pericyclases, enzymes that catalyze pericyclic reactions, form an expanding family of enzyme

126 r concerted reactions, such as S(N)2, E2, or pericyclic reactions, in such a way that atoms are invol

127 e conclude with perspectives on the field of pericyclic reactions, including a refinement as the mean

128 ly the XP-PCM method to a selection of other pericyclic reactions, including the parent Diels-Alder c

129 role of heavy-atom tunneling in the area of pericyclic reactions, pai-bond-shifting, and other proce

130 Olefin chemistry, through pericyclic reactions, polymerizations, oxidations, or re

131 s rational design of interrupted and aborted pericyclic reactions, using the Cope rearrangement as a

132 Pericyclic reactions-which proceed in a concerted fashio

133 tly are based on chiral Lewis acid catalyzed pericyclic reactions.

134 is a fundamental prototype of photochemical pericyclic reactions.

135 nchronous bond formation and breaking during pericyclic reactions.

136 estabilized 1-azapentadienium ions and their pericyclic reactions.

137 ective than bulk water for catalysis of such pericyclic reactions.

138 um mechanical cluster modeling, we propose a pericyclic rearrangement lyase mechanism for EPS1.

139 E. coli chorismate mutase (CM) catalyzes the pericyclic rearrangement of chorismate to prephenate.

140 ion states are characteristic of a concerted pericyclic rearrangement.

141 ry can also be applied successfully to other pericyclic shifts such as [1,5]-shifts which involve chl

142 migration of two hydrogen atoms/groups in a pericyclic [sigma2s + sigma2s + pi2s] reaction through s

143 his way the bond cleavage is promoted by the pericyclic stabilization of the [2,3] transition state.

144 ce involves (1) consecutive but not combined pericyclic steps, a coarctate TS, and pseudopericyclic m

145 ldoximes react to both heat and light with a pericyclic syn elimination, while carbamoylketoximes und

146 the 3 --> 4 electrocyclization (essentially pericyclic), the 11 --> 12 [3,3] sigmatropic rearrangeme

147 propriately aligned in an exo orientation, a pericyclic three-bond cleavage occurs.

148 tereoselective dehydration followed by three pericyclic transformations: intramolecular Diels-Alder a

149 nsition states is contrasted with the single pericyclic transition state (15TS) for the electrocyclic

150 ly affects the branching ratio after the bis-pericyclic transition state and ultimately reverses the

151 y the electronic nature of substituents, the pericyclic transition state can become an energy minimum

152 This structure is known as a pericyclic transition state for thermal reactions and a

153 t a majority of downhill paths after the bis-pericyclic transition state lead to the Diels-Alder cycl

154 studies suggest that neither a six-membered pericyclic transition state nor any multibond concerted

155 cases, only a single highly asynchronous bis-pericyclic transition state yielding both Diels-Alder an

156 C-C bond formation through a seven-membered pericyclic transition state.

157 This can be rationalized by invoking a bis-pericyclic transition state.

158 nd an electron-deficient alkene via a single pericyclic transition state.

159 ransition states appear when two independent pericyclic transition states merge into one.

160 n the opposite direction compared to the bis-pericyclic transition states.

161 nsition states now known as ambimodal or bis-pericyclic transition states.

162 an aborted [3,3] sigmatropic shift where the pericyclic "transition state" becomes the most stable sp

163 pen new avenues for addressing challenges in pericyclic Umpolung and regioselectivity control.

164 ndered nucleophilic (or vice versa), and (2) pericyclic Umpolung, in which the regioselectivity of pe

165 and 19 --> 20 rearrangements are classically pericyclic, whereas the 15 --> 16 rearrangement is pseud