Highly stereoselective radical cyclization: copper or ruthenium-catalyzed preparation of cis- and trans-.beta.,.gamma.-dialkyl .gamma.-lactams from acyclic N-allyltrichloroacetamide derivatives
A reductive dicarbofunctionalization reaction of alkenes has been developed and applied to the preparation of substituted carbo- and heterocycles. The reaction conditions avoid the use of air-sensitive organometallic reagents, and are compatible with a broad range of bromo-electrophiles and a wide variety of substituents to give cyclic products in excellent yields.
Highly stereoselective radical cyclization: copper or ruthenium-catalyzed preparation of cis- and trans-.beta.,.gamma.-dialkyl .gamma.-lactams from acyclic N-allyltrichloroacetamide derivatives
Cobalt-Catalyzed Tandem Radical Cyclization/C–C Coupling Initiated by Directed C–H Activation
作者:Qiao Sun、Naohiko Yoshikai
DOI:10.1021/acs.orglett.9b01846
日期:2019.7.5
A cobalt–N-heterocyclic carbene catalyst promotes a tandem radical cyclization/C–Ccoupling reaction between tosylamide-tethered bromo-alkenes and aryl N–H imines initiated by chelation-assisted arene C–Hactivation, affording 3-(arylmethyl)pyrrolidine derivatives in moderate to good yields. The reaction tolerates a variety of substituents on the aryl imine as well as various modifications on the bromo-alkene
Transition metal-catalyzed radical cyclizations: a low-temperature process for the cyclization of N-protected N-allyltrichloroacetamides to trichlorinated .gamma.-lactams and application to the stereoselective preparation of .beta.,.gamma.-disubstituted .gamma.-lactams
Cyclizations of N-substituted N-allyltrichloroacetamides, where the substituent is an alkyl, Cbz, Boc, Ts, or Ms group, are catalyzed by a 1:1 mixture of CuCl and bipyridine to give the corresponding beta,gamma-trichlorinated gamma-lactams in high yields. The reactions proceed at temperatures from -78-degrees-C to room temperature. Cyclizations of N-allyltrichloroacetamides of acyclic secondary allylic amines are achieved with good selectivity; the cis/trans ratios of the gamma-lactams formed were dependent on the substituents on the nitrogen atom. The stereochemical outcome is compared with that of free-radical cyclization.