Reductive Cyclization of Dimethyl Diallylmalonate Catalyzed by Palladium−Bisoxazoline Complexes in the Presence of Silane and Water

Abstract

Reaction of dimethyl diallylmalonate (1) with a stoichiometric amount of water and HSiEt3 catalyzed by a 1:1 mixture of (N−N)Pd(Me)Cl [N−N = 4,4‘-dibenzyl-4,5,4‘,5‘-tetrahydro-2,2‘-bisoxazoline] (4a) and NaBAr4 [Ar = 3,5-C6H3(CF3)2] at 50 °C in 1,2-dichloroethane led to the isolation of a 4.4:1 mixture of trans-dimethyl-3,4-dimethylcyclopentane-1,1-dicarboxylate (5) (≥ 95% de, 38% ee) and dimethyl dipropylmalonate (6) in 88% combined yield. Reaction of 1 with a stoichiometric mixture of D2O/HSiEt3 or H2O/DSiEt3 catalyzed by 4a/NaBAr4 formed predominantly the 5-d1 isotopomer, which possessed a single deuterium atom at one of the exocyclic methyl groups. Reaction of 1 with a stoichiometric mixture of D2O/DSiEt3 catalyzed by 4a/NaBAr4 formed predominantly the 5-d2 isotopomer with a single deuterium atom at each of the exocyclic methyl groups.