Stereospecific, Nickel-Catalyzed Suzuki–Miyaura Cross-Coupling of Allylic Pivalates To Deliver Quaternary Stereocenters
摘要:
Recognizing the importance of all-carbon, quaternary stereocenters in complex molecule synthesis, a stereospecific, nickel-catalyzed cross-coupling of allylic pivalates with arylboroxines to deliver products equipped with quaternary stereocenters and internal alkenes was developed. The enantioenriched allylic pivalate starting materials are readily prepared, and a variety of functional groups can be incorporated on both the allylic pivalate and the arylboroxine. Additional advantages include the use of a commercially available and air-stable Ni(II) salt and BISBI ligand, mild reaction conditions, and high yields and ee's. The observed stereoinversion of this reaction is consistent with an open transition state in the oxidative addition step.
Platinum-Catalyzed Addition of Dimethylsilylene to β-Methyl α,β-Unsaturated Ketones: γ-Silylation Forming 1-Oxa-2-silacyclohex-5-enes
作者:Kazuhiro Okamoto、Tamio Hayashi
DOI:10.1021/ol702357n
日期:2007.11.1
The reaction of beta-methyl alpha,beta-unsaturated ketones with pentamethyldisi lane in the presence of a platinum catalyst brought about silylation on the beta-methyl group giving high yields of oxasilacyclohexenes.