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101.
Stphanie Goumri‐Magnet Heinz Gornitzka Antoine Baceiredo Guy Bertrand 《Angewandte Chemie (International ed. in English)》1999,38(5):678-680
The first crystallographically characterized phosphonium yldiide 2 was obtained in a simple reaction by addition of n‐butyllithium to the stable phosphanyl(silyl)carbene 1 . R=cHex2N. 相似文献
102.
Maciej Saktura Anna Skrzyska Sebastian Frankowski Sylwia Wdka ukasz Albrecht 《Molecules (Basel, Switzerland)》2021,26(16)
In our studies, the organocatalytic 1,3-dipolar cycloaddition between 2-nitrobenzofurans or 2-nitrobenzothiophene and N-2,2,2-trifluoroethyl-substituted isatin imines has been developed. The reaction has been realized by employing bifunctional organocatalysis, with the use of squaramide derivative being crucial for the stereochemical efficiency of the process. The usefulness of the cycloadducts obtained has been confirmed in selected transformations, including aromative and non-aromative removal of the nitro group. 相似文献
103.
The regio- and chemoselective polar [3+2] cycloaddition (32CA) of the Padwa carbonyl ylide (CY) with α-methylene ketone (αMK) to yield the oxa-bridged spirocycloadduct has been studied using the DFT method at the B3LYP/6-31G(d) computational level. Six reactive channels associated to the stereo-, regio-, and chemoselective approach modes of the CY to the CC and CO reactive sites of the αMK have been analyzed. DFT calculations for this cycloaddition are in complete agreement with the experimental outcome, explaining the reactivity and selectivity of the formation of the [3+2] cycloadduct. Analysis of the global and local electrophilicity and nucleophilicity indices allows an explanation about the regio- and chemoselectivity of this 32CA reaction. Intrinsic reaction coordinate (IRC) calculations and the topological analysis of the electron localization function (ELF) of the relevant points of the favored reactive channel explain the one-step two-stage nature of the mechanism of this cycloaddition. 相似文献
104.
105.
Hai‐Yang Wang Dr. Fei Yang Xin‐Liang Li Dr. Xue‐Ming Yan Zhi‐Zhen Huang Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(15):3784-3789
A new strategy for the highly stereoselective synthesis of three stereoisomers of chiral 1,2,3‐trisubstituted cyclopropanes in good yields with excellent diastereoselectivities and very high enantioselectivities (up to >99 % ee) was developed via selenonium ylides (see scheme). Possible pathways for the asymmetric cyclopropanations were also proposed.
106.
3-Methylsulfanyl-2-arylazo-3-(pyrrolidin-1-yl)acrylonitriles do not enter into [4+2]-cycloaddition reactions with maleimides to form the expected pyrrolo-pyridazines. Instead the formation of novel pyrrolo-pyridazines of type 4 takes place via a formal [3+2]-cycloaddition of initially formed pyrrolidine-derived azomethine ylides 7. The mechanism leading to the final product is discussed. 相似文献
107.
Pei-Shan Wu Yan-Cheng Liou Gangababu Marri Yi-Ru Chen Jia-Rong Wu Wenwei Lin 《中国化学会会志》2023,70(12):2136-2146
An efficient synthesis of chromeno[4,3-b]pyrrolidines has been successfully developed. This strategy involves a base-catalyzed reaction of p-VQMs and o-hydroxy azomethine ylides via (3 + 2) cycloaddition/oxa-1,6-addition reaction sequence. The reaction condition is mild, and a series of chromeno[4,3-b]pyrrolidines were obtained in 49-95% yields with excellent diastereoselectivity (dr > 20:1). 相似文献
108.
The principal direction in the photolytic decomposition of 4-azidotetrachloropyridine in methylene chloride solution involves the intermediate formation of singlet tetrachloropyridyl-4-nitrene, the lifetime of which amounts to 50 nsec. The nitrene reacts readily with the pyridine (k
pyr = 2.67·107 mole-1·sec-1) with the formation of the corresponding pyridinium ylide, which has a characteristic absorption band in the UV spectrum with a maximum at 406 nm. 相似文献
109.
110.
Maghsoodlou MT Habibi-Khorassani SM Heydari R Hassankhani A Marandi G Nassiri M Mosaddeg E 《Molecular diversity》2007,11(2):87-91
A new one-pot, simple and effective procedure is presented for the preparation of O-containing phosphorus ylides by the Michael
addition reaction of N-methylpyrrole-2-carbaldehydoxime, pyridin-2-carbaldehydoxime or acetophenonoxime with acetylenic esters. 相似文献