Direct, enantioselective α-alkylation of aldehydes using simple olefins
作者:Andrew G. Capacci、Justin T. Malinowski、Neil J. McAlpine、Jerome Kuhne、David W. C. MacMillan
DOI:10.1038/nchem.2797
日期:2017.11
olefins as coupling partners. Chiral imidazolidinones or prolinols, in combination with a thiophenol, iridium photoredox catalyst and visible light, have been successfully used in a triple catalytic process that is temporally sequenced to deliver a new hydrogen and electron-borrowing mechanism. This multicatalytic process enables both intra- and intermolecular aldehyde α-methylene coupling with olefins
Aldehydes are obtained with linear to branched ratios up to >99:1. With styrene derivatives also the corresponding benzaldehydes are formed. The catalyst can be separated by extraction of the organic products with hexane and recycled for at least four times with only a modest loss of activity and no effect on selectivity.
Intramolecular [4+2]-cycloadditions of nitroalkenes with olefins. 2
作者:Scott E. Denmark、Young-Choon Moon、Christopher J. Cramer、Michael S. Dappen、C.B.W. Senanayake
DOI:10.1016/s0040-4020(01)89054-2
日期:1990.1
The intramolecular [4+2]-cycloadditions of di- and trisubstituted nitroalkenes with unactivated olefins are described. The cycloadditions proceed readily at low temperatures in the presence of SnCl4. The reactions are shown to be stereospecific in the preservation of dienophile configuration in the product. The configuration of the heterodiene controls the stereochemistry of the ring fusion but the
申请人:SHELL INTERNATIONALE RESEARCH
MAATSCHAPPIJ B.V.
公开号:EP0423874A2
公开(公告)日:1991-04-24
The invention provides novel unsaturated monoaldehydes of general formula
R¹-CH₂-CH(R²)-(CH₂)n-CH=C(CH₃)₂
wherein one of groups R¹ and R² represents a formyl group and the other represents a hydrogen atom and n is an integer from 2 to 8, preferably from 3 to 6, which compounds may be used as fragrants.
The invention further relates to a hydroformylation process for the preparation of the novel unsaturated aldehydes.