Efficient Rhodium‐Catalyzed Conjugate Addition of Arylboronic Acids to Unsaturated Furano Esters for the Highly Stereoselective Synthesis of Four Natural Trisubstituted Furanolignans

Abstract

Abstract Four natural lignans, (±)‐dihydrosesamin ( 1a ), (±)‐lariciresinol methyl ether ( 1b ), (±)‐sanshodiol methyl ether ( 1c ) and (±)‐acuminatin methyl ether ( 1d ), were prepared stereoselectively in five steps from a 4‐(arylmethylene)‐2‐methoxytetrahydrofuran derivative obtained by a MCR reaction. The key step of this synthesis is the microwave‐assisted stereoselective addition of a boronic acid (Hayashi–Miyaura reaction) to a 4‐ethoxycarbonyldihydrofuran, generating three contiguous stereogenic centers with an excellent diastereoselectivity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)