A concise asymmetric synthesis of naturally occurring bioactive 2,7′-cyclolignans, namely 4,4′-dihydroxy-3′,5,5′-trimethoxy-2,7′-cyclolignan and 4,4′-dihydroxy-3,3′,5-trimethoxy-2,7′-cyclolignan, possessing the uncommon 8,8′-syn dimethyl stereochemistry and unsymmetrical C-6 units with 7′,8′-anti-orientation is described using a substrate-controlled stereoselective Friedel-Crafts cyclization as the key step. The products were obtained in good yields with high stereoselectivity. The absolute configurations of natural 4,4′-dihydroxy-3′,5,5′-trimethoxy-2,7′-cyclolignan and those of natural 4,4′-dihydroxy-3,3′,5-trimethoxy-2,7′-cyclolignan were assigned as (7′S,8S,8′S) and (7′R,8R,8′R), respectively, based on the experimental circular dichroism (CD) spectra of the corresponding synthesized compounds.

天然存在的生物活性2,7'-cyclolignans的简明不对称合成，即4,4'-dihydroxy-3'，5,5'-trimethoxy-2,7'-cyclolignan和4,4'-dihydroxy-3,3使用受底物控制的立体选择性Friedel- F描述了具有罕见的8,8'-顺二甲基立体化学和具有7'，8'-反取向的不对称C-6单元的'，5-三甲氧基-2,7'-cyclolignan。工艺环化是关键步骤。以高产率获得具有高立体选择性的产物。天然4,4'-二羟基-3'，5,5'-三甲氧基-2,7'-cyclolignan和天然4,4'-二羟基-3,3'，5-三甲氧基-2的绝对构型7'-cyclolignan被指定为（7 'S，8 S，8 'S）和（7'R，8R，8'R），分别基于相应合成化合物的实验圆二色性（CD）光谱。