The asymmetric synthesis of aryltetralin lignans: (−)-isolariciresinol dimethyl ether and (−)-deoxysikkimotoxin

The total asymmetric syntheses of (−)-isolariciresinol dimethyl ether (6) and (−)-deoxysikkimotoxin (7) have been carried out, in an attempt to exploit a synthetic strategy recently developed for the synthesis of (−)-deoxypodophyllotoxin (1, R1 = -CH2−, Ar = 3,4,5-trimethoxyphenyl). In so doing, a generalized method for the synthesis of aryltetralin lignans has been developed that should be applicable to a variety of substitution patterns and stereochemistries. A one-pot, 100% regio-selective reduction–lactonization procedure has been developed for the conversion of the ester 18b to (−)-deoxysikkimotoxin, which gave 93% isolated yield in that step.