Reactions of diphenylphosphinoyl radicals with 5-aryl-2-pentenoates or beta-phenylethylene styrenes generate trans-substituted tetrahydronaphthalenes through a cascade reaction sequence.
skeletons of dialkyl sulfates, primary allyl halides, and benzyl bromides were transferred to the α-position of the substrates to provide products in moderate to good yields with a diastereoselectivity of >95% in most cases. Substrates bearing a β-(hetero)aryl substituent gave higher diastereoselectivities than those bearing a linear β-alkyl substituent. The crystal structure of the potassium trifluoroborate
Selective .gamma. alkylation of copper enolates derived from .alpha.,.beta.-unsaturated acids: factors affecting scope and regio- and stereoselectivity
作者:Patricia M. Savu、John A. Katzenellenbogen
DOI:10.1021/jo00315a003
日期:1981.1
(<i>Z</i>)-α-Haloacrylates: An Exceptionally Stereoselective Preparation via Cr(II)-Mediated Olefination of Aldehydes with Trihaloacetates
作者:D. K. Barma、Abhijit Kundu、Hongming Zhang、Charles Mioskowski、J. R. Falck
DOI:10.1021/ja029938d
日期:2003.3.1
(Z)-alpha-Fluoro-, (Z)-alpha-chloro-, and (Z)-alpha-bromoacrylates were obtained with unprecedented yield and stereocontrol (>99%) via addition of the corresponding commercial trihaloacetates to aldehydes at room temperature using stoichiometric Cr(II) salts or catalytic Cr(II) with a regeneration system. The intermediate 2,2-dihalo-3-hydroxy adducts could be isolated in good yields under conditions of limited reagent at 0 degrees C.
SAVU P. M.; KATZENELLENBOGEN J. A., J. ORG. CHEM., 1981, 46, NO 2, 239-250