具有≥96% 对映体过量的 α,β-丁烯内酯是由 β,γ-丁烯内酯通过新型 Cu(I)-配体协同催化合成的。该反应由具有远程叔氨基的手性联苯-2-基膦配体实现。密度泛函理论研究支持金属中心和配体碱性氨基在初始软去质子化和关键不对称γ-质子化过程中的合作。值得注意的是,其他造币金属,即 Ag 和 Au,在这种不对称异构化化学中可以很容易地承担与 Cu 相同的作用。
The asymmetric synthesis of γ-alkenyl butenolides was accomplished by conjugatedaddition of butenolides to alkynones. Both terminal alkynones and nonterminal alkynones were applicable to the N,N′-dioxide–scandium(III) catalytic system. The corresponding products were obtained in good to excellent yields (up to 99%) with high E/Z ratios and high enantioselectivities (up to 98% ee). The novel methods
An asymmetric direct vinylogous aldol reaction between isatins and β,γ-unsaturated butenolides has been developed with a N,N’-dioxide-Sc(OTf)3 complex as catalyst. A variety of δ-hydroxy butenolides bearing congested adjacent tetrasubstituted stereocenters were obtained in good yields with high diastereoselectivities and excellent enantioselectivities
AbstractA highly efficient N,N′‐dioxide–scandium(III) complex catalytic system has been developed for the asymmetric vinylogous Michael reaction of α‐angelica lactone and its derivatives to α,β‐unsaturated γ‐keto esters, affording the corresponding γ,γ‐disubstituted butenolide products in moderate to good yields (up to 93%) with high dr (up to >19:1) and ee values (up to 97%) under mild reaction conditions.magnified image
DAURIA, M.;DE, MICO, A.;PIANCATELLI, G.;SCETTRI, A., TETRAHEDRON, 1982, 38, N 11, 1661-1666
作者:DAURIA, M.、DE, MICO, A.、PIANCATELLI, G.、SCETTRI, A.
DOI:——
日期:——
A facile route to 5-alkyl-2(3H)-furanones by photoisomerisation of enedicarbonyl compounds
作者:M. D'Auria、A. De Mico、G. Piancatelli、A. Scettri
DOI:10.1016/0040-4020(82)80143-9
日期:1982.1
A new and useful synthesis of a title compounds is reported. They can be obtained easily by photocyclization of enedicarbonylcompounds 3 and 4. A different behaviour, ascribed to the geometry of a double bond, is observed; 3 are converted only to butenolides 5, while trans-isomers 4 are converted into alkyl-furyl-ketones 5 and 6. A possible mechanism is described.