ライフサイエンスコーパス: electrocyclic

1 tization-triggered C-O bond cleavage, and an electrocyclic 4n-ring-opening of oxetene intermediate.

2 e synthesized and employed for light-induced electrocyclic 4pi ring closure leading to bicyclo-beta-l

3 ated (large) differences in barriers between electrocyclic and sigmatropic pathways.

4 emperature, the allenyl compounds undergo an electrocyclic cascade to give bicyclo[4.2.0]octadienyl-f

5 proceeds to the major product by sequential electrocyclic closure and a 1,2-shift, rather than the e

6 d quantum chemical modeling point instead to electrocyclic closure and aromatization of the heptameth

7 Along a competitive pathway, electrocyclic closure to an isophenanthrene is predicted

8 The orbital symmetry forbidden thermal electrocyclic equilibria between a series of cyclophaned

9 Torquoselectivity in the electrocyclic interconversions of 1-azapolyenes and thei

10 thienylimidazolium salt was found to undergo electrocyclic isomerization upon exposure to UV radiatio

11 synthesized and found to undergo reversible electrocyclic isomerization upon successive exposure to

12 ally a transition state in their stress-free electrocyclic isomerization.

13 metal center, which likely occurs through an electrocyclic mechanism analogous to a Nazarov cyclizati

14 position of unsaturation consistent with an electrocyclic mechanism of 1,4-dihydrogen elimination.

15 anion that cyclizes either by a suprafacial electrocyclic mechanism, or through a kinetically contro

16 e other we propose to proceed through a 6pai electrocyclic mechanism.

17 The electrocyclic nature of the ring-closing reactions was s

18 An electrocyclic pathway via an electrocyclic ring opening

19 the difference between allowed and forbidden electrocyclic reaction barriers, and we provide computat

20 rationalized in terms of a Nazarov-type 4pi-electrocyclic reaction followed by pi-cyclization onto t

21 The semiquinone species undergo a type of electrocyclic reaction known as a 1,5-sigmatropic shift

22 t cryogenic temperatures due to a reversible electrocyclic reaction of its carbon skeleton.

23 enyl is more likely the result of a distinct electrocyclic reaction than quenching of a two-step mech

24 a series of photochemical E-Z isomerization, electrocyclic reaction, and oxidation steps in a stepwis

25 nges to a boranorcaradiene by a thermal 6pai-electrocyclic reaction.

26 Electrocyclic reactions are characterized by the concert

27 nd the first step of the mechanism, and both electrocyclic reactions are favored by coordination to t

28 These findings may be transferrable to electrocyclic reactions in general.

29 ohexadiene constitutes a textbook example of electrocyclic reactions in organic chemistry and a model

30 Drafts of the Stereochemistry of Electrocyclic Reactions paper and letters and notes by W

31 The process involves four consecutive electrocyclic reactions to convert all chromophores betw

32 We now report an investigation of various electrocyclic reactions using DFT and CASSCF.

33 dward-Hoffmann paper, The Stereochemistry of Electrocyclic Reactions, ushered into organic chemistry

34 d a theory to predict the stereochemistry of electrocyclic reactions, which, after expansion and gene

35 o explain and predict the stereochemistry of electrocyclic reactions.

36 and the origin of torquoselectivity in these electrocyclic reactions.

37 e energies for the E-Z isomerization and the electrocyclic reactions; the reverse processes for the s

38 he 6-31G* basis set, was used to examine six electrocyclic rearrangements, each involving a 1,2,4,6-h

39 rminal alkyne and sulfonyl azide followed by electrocyclic ring closure and aromatization.

40 ing experiments show that 4 does not undergo electrocyclic ring closure but reacts exclusively by pho

41 rmation of the enamine is such that a facile electrocyclic ring closure is ensured, which is corrobor

42 An electrocyclic ring closure is the key step of an efficie

43 The electrocyclic ring closure occurs in the singlet excited

44 t that a highly stereoselective 6pi-electron electrocyclic ring closure of 1-azatrienes is a key step

45 he first highly stereoselective 6pi-electron electrocyclic ring closure of 1-azatrienes.

46 An electrocyclic ring closure of a 2-azapentadienyl anion g

47 alculations on the potential surface for the electrocyclic ring closure of E-7-azahepta-1,2,4,6-tetra

48 quinone unit by an extremely facile oxa-6pi-electrocyclic ring closure reaction of an ortho-quinone

49 8 can be explained in terms of photoinduced electrocyclic ring closure resulting in the formation of

50 onosubstituted tetraenes readily undergo 8pi electrocyclic ring closure to form 1,3,5-cyclooctatriene

51 e substituent, the enamines undergo a facile electrocyclic ring closure to form a cyclohexadiene, whi

52 s to give the photoaddition product; and (3) electrocyclic ring closure to give benzoxanthene derivat

53 went either reverse proton transfer (RPT) or electrocyclic ring closure to give dihydrobenzoxanthenes

54 ion to give a QM that underwent quantitative electrocyclic ring closure to give the corresponding ben

55 , PhCH2CO2(-), PhO(-)) undergo photochemical electrocyclic ring closure to produce a zwitterionic int

56 n situ with multiple nucleophiles or undergo electrocyclic ring closure to yield hydroxynaphthalenes

57 involves an E-Z alkene isomerization, a 6pi electrocyclic ring closure, a [1,5]-sigmatropic shift of

58 for rotation around the exocyclic C==N bond, electrocyclic ring closure, and loss of N(2) were calcul

59 ) reveal that in the transition state of 4pi electrocyclic ring closure, the oxazolidinone ring and t

60 hiazole undergoes phototransposition via the electrocyclic ring closure-heteroatom migration pathway

61 ism, elimination of acetic acid, and a final electrocyclic ring closure.

62 sults (M06-2X/cc-pVDZ) on rate constants for electrocyclic ring closures and [3,3] sigmatropic shifts

63 thermochemistry and transition states of the electrocyclic ring closures of the resonance-stabilized

64 ese azaelectrocyclizations, we modeled these electrocyclic ring closures using the M06-2X density fun

65 f a formal [2 + 2]-cycloaddition followed by electrocyclic ring opening and a terminating [4 + 2]-typ

66 -1,2,4,6-tetraen-1,7-dione (17a) by means of electrocyclic ring opening followed by a facile 1,5-H sh

67 An electrocyclic pathway via an electrocyclic ring opening followed by a ring flip and a

68 nzocyclobutene undergo an ultrasound-induced electrocyclic ring opening in a formally conrotatory and

69 the calculated barrier for a subsequent 4pai electrocyclic ring opening leading to the observed imino

70 rtion, and aromatic C-C double bond addition/electrocyclic ring opening obey saturation (Michaelis-Me

71 Electrocyclic ring opening of 4,6-fused cyclobutenamides

72 ence of N-methylation, cyanide addition, and electrocyclic ring opening of a 4-oxazoline intermediate

73 N(-) to produce the azomethine ylide 24b via electrocyclic ring opening of an oxazoline 23b.

74 The thermal electrocyclic ring opening of fused cis-cyclobutene to c

75 s that the force-induced acceleration of the electrocyclic ring opening of gem-dichlorocyclopropanes

76 ep process involves three cycloadditions and electrocyclic ring opening of the strained Dewar anthrac

77 rmediates (perhaps the result of 10-electron electrocyclic ring opening of the tetraene 8), synthetic

78 n is of little consequence to the subsequent electrocyclic ring opening that forges the pyridine core

79 diazacyclobutene formation primed for rapid electrocyclic ring opening to an alpha-iminothioimidate

80 ding through formal [2+2] cycloaddition, 4pi-electrocyclic ring opening, and 6pi-electrocyclic ring-c

81 de reaction involving a Michael addition-6pi-electrocyclic ring opening-proton transfer and 6pi elect

82 igmatropic hydrogen shift and a two-electron electrocyclic ring opening.

83 nulation reaction involves photoinduced 6pai-electrocyclic ring-closing and hydrogen evolution cascad

84 ion, 4pi-electrocyclic ring opening, and 6pi-electrocyclic ring-closing events, constitutes a robust

85 ission, and photochemical dynamics of the 4n-electrocyclic ring-closing of hexafluorobenzene and the

86 , electrocyclic ring-opening of cyclobutene, electrocyclic ring-closing of Z-hexatriene, the [1,5]-H

87 he activation energy for the subsequent 6pai-electrocyclic ring-closure is lower than that for relate

88 l condensation and a reversible 6pi-electron electrocyclic ring-closure of 1-oxatrienes.

89 d mechanism of a 4pi-conrotatory Mobius-type electrocyclic ring-closure reaction.

90 d n-system in polyenes can be interrupted by electrocyclic ring-closure reactions.

91 of three n-bonds and generally promoting 6n-electrocyclic ring-closure reactions.

92 s of diynes and aldehydes afforded the [3,3] electrocyclic ring-opened tautomers, rather than pyrans,

93 e two possibilities, an allowed six-electron electrocyclic ring-opening is predicted to be highly fav

94 ecedented, unique domino Suzuki-Miyaura/4pai-electrocyclic ring-opening macrocyclization, resulting i

95 er cycloaddition of butadiene with ethylene, electrocyclic ring-opening of cyclobutene, electrocyclic

96 e pericyclic transition state (15TS) for the electrocyclic ring-opening of oxetene (15) to acrolein (

97 teps in the evolution of this system are the electrocyclic ring-opening of the 2H-pyran to a alpha-me

98 tep following benzyne generation is the 4pai-electrocyclic ring-opening of the alkynylbenzocyclobuten

99 etween substituent groups destabilize the 4n-electrocyclic ring-opening pathway and minimum energy co

100 xide systems show that the thermally allowed electrocyclic ring-opening pathway is favored by less th

101 osed-shell repulsions block a 6n-conrotatory electrocyclic ring-opening pathway with increasing steri

102 gh the pericyclic minimum of a photochemical electrocyclic ring-opening reaction in the molecule alph

103 The ultrafast light-activated electrocyclic ring-opening reaction of 1,3-cyclohexadien

104 at both processes may occur by a 10-electron electrocyclic ring-opening reaction of eta(2)-organocoba

105 are used to study the stereochemistry of the electrocyclic ring-opening reaction of the cyclopropyl r

106 changes colour as it undergoes a reversible electrocyclic ring-opening reaction under tensile stress

107 -phase elimination of ethylene, a concerted, electrocyclic ring-opening reaction.

108 nvestigation of a-phellandrene undergoing an electrocyclic ring-opening reaction.

109 eaction energetics and transition states for electrocyclic ring-opening reactions of 3-silyl, fluoros

110 rts of inward torquoselectivities in thermal electrocyclic ring-opening reactions of 3-silylcyclobute

111 Transition structures for the conrotatory electrocyclic ring-opening reactions of N-substituted 2-

112 understanding of force-modified pathways for electrocyclic ring-opening reactions.

113 of a Rh-mediated intramolecular Buchner/6pai-electrocyclic ring-opening sequence enabled construction

114 to proceed through a mechanism involving an electrocyclic ring-opening step.

115 oxetenes are formed and subsequently undergo electrocyclic ring-opening to methyl vinylketones.

116 e product: (1) thermally allowed conrotatory electrocyclic ring-opening, (2) thermally forbidden disr

117 a [1,5]-sigmatropic shift of hydrogen, a 6pi electrocyclic ring-opening, and a Diels-Alder cycloaddit

118 ce for a pathway that avoids metal-templated electrocyclic ring-opening, but the pericyclic pathway i

119 ropyl-I((III)) intermediates able to undergo electrocyclic ring-opening, following the Woodward-Hoffm

120 opening, (2) thermally forbidden disrotatory electrocyclic ring-opening, or (3) nonpericyclic C-C bon

121 jectories proceed through the 6n-conrotatory electrocyclic ring-opening, whereas the trifluoromethyl-

122 earranges to 1,2-dimethylenecyclopentane via electrocyclic ring-opening.

123 Key transformation involves an oxa-6pi electrocyclic ring-opening/hetero-Diels-Alder pericyclic

124 e to 12-annulenes, sigmatropic 1,5-H-shifts, electrocyclic ring-openings of the 6-membered rings, and

125 rate differences between normal and anionic electrocyclic ring-openings.

126 The free-energy barrier for this electrocyclic route was shown to be very close to the bi