Results 171 to 180 of about 4,396,712 (209)

A non-Woodward and Hoffmann reaction path for photochemical sigmatropic rearrangements

Journal of Molecular Structure: THEOCHEM, 1985
The semi-empirical MNDO-SCF method, extended with a limited (3 × 3) CI, has been used to calculate the photochemical (1, 3) shifts in propene, 2-propen-1-ol, 1-butene and the (1, 5) shifts in 1,3-pentadiene and 1,3-hexadiene. The suprafacial and antarafacial reactions as considered by Woodward and Hoffmann are compared with a planar shift which is ...
Guido J.M. Dormans, Willie J.G.M. Peijnenburg, H. M. Buck   +2 more
openaire   +3 more sources

Application of a tandem electrocyclic [3,3]sigmatropic reaction of o-quinodimethane to the synthesis of calabar bean alkaloids. Part 2. First total synthesis of (±)-geneserine

, 1987
The first total synthesis of the Calabar bean alkaloid geneserine (1) starting with 1-cyano-5-methoxybenzocyclobutene (7) has been accomplished via a 16-step sequence in 27% overall yield.
K. Shishido, K. Hiroya, H. Komatsu, K. Fukumoto*, T. Kametani   +4 more
semanticscholar   +1 more source

Electrochemical Allylic C(sp3)-H Isothiocyanation via [3,3]-Sigmatropic Rearrangement.

Organic Letters
The direct allylic C(sp3)-H functionalization provides a straightforward protocol for the synthesis of valuable molecules. We report herein the first chemo- and site-selective method for allylic C(sp3)-H isothiocyanation of various internal alkenes under
Xuezhuang Gao, Hui He, Kaili Miao, Linbao Zhang, Shao-Fei Ni, Ming Li, Weisi Guo   +6 more
semanticscholar   +1 more source

Asymmetric Iodonio-[3,3]-Sigmatropic Rearrangement to Access Chiral α-Aryl Carbonyl Compounds.

Journal of the American Chemical Society, 2020
Here we describe an asymmetric [3,3]-sigmatropic rearrangement of aryl iodanes that enables the enantioselective α-arylation of chiral 2-oxazolines, thereby producing valuable, chiral α-aryl carbonyl compounds.
Junsong Tian, Fan Luo, Qifeng Zhang, Yuchen Liang, Dongyang Li, Yaling Zhan, Lichun Kong, Zhi‐Xiang Wang, Bo Peng   +8 more
semanticscholar   +1 more source

Pericyclic Reactions: Cycloadditions, Electrocyclic Reactions, and Sigmatropic Rearrangements

2013
This chapter covers pericyclic reactions and their its types. In these so-called pericyclic reactions, all the bond forming and bond breaking occurs together with a nonpolar, concerted cyclic redistribution of valence electrons via aromatic transition structures.
Tadashi Okuyama, Howard Maskill
openaire   +1 more source

Tandem Electrocyclic‐Sigmatropic Reaction of Benzocyclobutenes.

, 1986
Das Methoxybenzocyclobuten (I) wird uber die Kondensationsprodukte (II) zu den Aldehyden (III) umgesetzt, die nach Grignard die Alkohole (V) ergeben, welche mit KOH/EtOH zu den Lactonen (VI) cyclisiert werden.
K. Shishido, K. Hiroya, K. Fukumoto*, T. Kametani   +3 more
semanticscholar   +1 more source

Studies dealing with cycloaddition and sigmatropic reactions of cyclopropenyl-substituted indenes

The Journal of Organic Chemistry, 1991
AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Diana M. Cordova, Albert Padwa, Mitchell Pulwer   +2 more
openaire   +3 more sources

Z-Selective  α-Arylation of α,β-Unsaturated Nitriles via [3,3]-Sigmatropic Rearrangement.

Angewandte Chemie, 2020
Morita-Baylis-Hillman (MBH) reaction and [3,3]-sigmatropic rearrangement are two paradigms in organic synthesis. By merging the two types of reactions, we herein describe [3,3]-rearrangement of aryl sulfoxides with α,β-unsaturated nitriles.
Mengyuan Chen, Yuchen Liang, Taotao Dong, Weijian Liang, Yanping Liu, Yage Zhang, Xin Huang, Lichun Kong, Zhi‐Xiang Wang, Bo Peng   +9 more
semanticscholar   +1 more source

Sequence [2,3]‐Sigmatropic Rearrangement: One‐Pot Synthesis of Propargyl Allenylamines

Chinese journal of chemistry
Allenes, served as highly sought‐after building blocks, are an indispensable component of synthetic chemistry. Their utility in modulating the chemical, physical, and pharmaceutical properties of organic compounds make allenes a desirable choice in ...
Huihui Feng, Yujuan Xie, Liliang Huang, Yongqing Xu, Junhai Huang, H. Feng   +5 more
semanticscholar   +1 more source

The Reformatsky–Claisen reaction, a new synthetically useful sigmatropic process

J. Chem. Soc., Chem. Commun., 1973
Reaction of α-bromo-esters derived from allylic and acetylenic alcohols with zinc dust provides a useful synthesis of γδ-unsaturated acids, via[3,3]-sigmatropic rearrangement of the intermediate zinc enolate, the efficiency depending upon substitution and solvent.
Jack E. Baldwin, Jerry A. Walker
openaire   +2 more sources