Enantio- and Diastereoselective Organocatalytic α-Alkylation of Aldehydes with 3-Substituted 2-(Bromomethyl)acrylates
摘要:
The catalytic direct alpha-alkylation of aldehydes with 2-(bromomethyl)acrylates has been accomplished, giving rise to alpha-branched and functionalized aldehydes of high diastereo- and enantiopurity. The influence of the nature of the ester group of the acrylates in reaction stereoselectivity and especially in reactivity is investigated. Optimum conditions implicate the use of phenyl acrylates in conjunction with organocatalyst 8. Application of thus obtained adducts in synthesis is illustrated with a concise stereocontrolled preparation of trisubstituted cyclopentenes.
N-Heterocyclic Carbene Organocatalysts for Dehydrogenative Coupling of Silanes and Hydroxyl Compounds
作者:Dongjing Gao、Chunming Cui
DOI:10.1002/chem.201301893
日期:2013.8.19
Go organic! N‐Heterocyclic carbene (NHC) 1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene (IiPr) has been found to be an efficient and selective catalyst for the dehydrogenativecoupling of a wide range of silanes and hydroxyl groups to form SiO bonds under mild and solvent‐free conditions (see scheme). Mechanistic studies indicated that the activation of hydroxyl groups by the NHC is the most plausible