Visible‐Light‐Driven Strain‐Increase Ring Contraction Allows the Synthesis of Cyclobutyl Boronic Esters
作者:Raffael Davenport、Mattia Silvi、Adam Noble、Zied Hosni、Natalie Fey、Varinder K. Aggarwal
DOI:10.1002/anie.201915409
日期:2020.4.16
There are a limited number of ring-contraction methodologies which convert readily available five-membered rings into strained four-membered rings. Here we report a photo-induced radical-mediated ringcontraction of five-membered-ring alkenyl boronate complexes into cyclobutanes. The process involves the addition of an electrophilic radical to the electron-rich alkenyl boronate complex, leading to
Use of alkyl 2,4,6-triisopropylbenzoates in the asymmetric homologation of challenging boronic esters
作者:Robin Larouche-Gauthier、Catherine J. Fletcher、Irantzu Couto、Varinder K. Aggarwal
DOI:10.1039/c1cc14469c
日期:——
(-)-Sparteine induced lithiation of primary 2,4,6-triisopropylbenzoates and subsequent homologation of boronicesters is reported. A comparative study with lithiated N,N-diisopropylcarbamates has demonstrated the superiority of the hindered benzoate.
Synthesis and Homologation of an Azetidin-2-yl Boronic Ester with α-Lithioalkyl Triisopropylbenzoates
作者:Pascal K. Delany、David M. Hodgson
DOI:10.1021/acs.orglett.9b03901
日期:2019.12.20
loxy organolithiums to give homologated boronicesters that can be further oxidized, homologated, arylated, and deprotected to give a range of α-substituted azetidines. Scalemic α-boryl azetidine-α-triisopropylbenzoyloxy organolithium pairings show stereospecific reagent control, providing access to either diastereomeric series of homologated boronicesters with very high er's.