accomplished with a chiral Lewis base and a chiral Brønsted acid as cocatalysts, generating various β-arylthio ketones bearing an all-carbon quaternary center in moderate to excellent yields and excellent enantioselectivities. These chiral arylthio ketone products are common intermediates with many applications, for example, in the design of new chiral catalysts/ligands and the totalsynthesis of natural products
Halogen Cation Induced StereoselectiveSemipinacol-type Rearrangement of Allylic Alcohols: A Highly EfficientApproach to α-Quaternary β-Haloketo Compounds
作者:Yong Qiang Tu、Bao Min Wang、Zhen Lei Song、Chun An Fan、Wei Ming Chen
DOI:10.1055/s-2003-40855
日期:——
Allylic alcohols were found to undergo a semipinacol-type rearrangement induced by halogen cation generated from the chloramine-T/ZnX 2 combination, which provided a highly efficient and stereoselective method for the preparation of α-quatemary β-haloketo compounds. This reaction is valuable and versatile since a quaternary carbon could be constructed effectively and three kinds of β-haloketo compounds
electrophilic thiocyano semipinacolrearrangement of allylic alcohols has been achieved for the first time by using N-thiocyano-dibenzenesulfonimide (NTSI). This approach provides a direct, simple, and efficient strategy for the formation of thiocyano carbonyl compounds with moderate to excellent yields. Meanwhile, an all-carbon quaternary center was rapidly constructed. In addition, an asymmetric version of this
A novel tandem aziridination/rearrangement reaction of allylic alcohols has been discovered, in which the significant accelerating effect of silica gel has been identified. On the basis of this methodology, an efficient and highly stereoselectiveapproach to various 2-quaternary Mannich bases has been put in place, readily providing an alternative route to the conventional vicinal amino-functionalization