Competitive 3+2 and 2+2 cycloadditions of ester stabilized azaallyl anions to benzynes. Ring expansion of initial 3+2 products to isoquinolin-3-ones
作者:Helmi Hussain、Ebrahim Kianmehr、Tony Durst
DOI:10.1016/s0040-4039(01)00130-7
日期:2001.3
Reaction of the azaallyllithiums derived from imines of α-amino esters with benzynes results in the formation of 1,3-dihydroisoindoles and 4-hydroxyisoquinolines via 3+2 and 2+2 cycloadditions, respectively. The initially formed 1-carboethoxy-1,3-dihydroisoindoles rearrange under basic reaction conditions to form 3-(2H)-isoquinolinones.
An approach to the polycycliccore of sarain A, based upon a proposed biogenetic route, is presented. Condensation of a protected amino acid with a bromoacrylamide and subsequent addition of malonaldehyde sodium salt and methyl iodide afforded, after stereoselective hydrogenation, a highly functionalized diazabicyclo[4.3.0]nonane system 16. This intermediate possesses the stereochemistry required for
Stereocontrolled addition of organozinc reagents derived from 2-(bromomethyl)acrylates to chiral imines.
作者:Yénimégué A. Dembélé、Chantal Belaud、Peter Hitchcock、Jean Villiéras
DOI:10.1016/s0957-4166(00)80272-4
日期:1992.1
Stereocontrolled addition of isolated organozinc reagents derived from 2-(bromomethyl)acrylates to imines can be achieved with ee approximately 100% using alpha-amino esters as chiral auxiliaries. High yields of pure RR or SS N-substituted alpha-methylene gamma-lactams can be prepared by this method.