Diastereo- and Regioselective Addition of Thioamide Dianions to Imines and Aziridines: Synthesis of N-Thioacyl-1,2-diamines and N-Thioacyl-1,3-diamines

摘要

Addition reactions of thioamide dianions that were derived from N-arylmethyl thioamides to imines and aziridines were carried out. The reactions of imines gave the addition products of N-thioacyl-1,2-diamines in a highly diastereoselective manner in good-to-excellent yields. The diastereomeric purity of these N-thioacyl-1,2-diamines could be enriched by simple recrystallization. The reduction of Nthioacyl-1,2-diamines with LiAlH_4 gave their corresponding 1,2-diamines in moderate-to-good yields with retention of their stereochemistry. The oxidativedesulfurization/cyclization of an Nthioacyl-1,2-diamine in CuCl_2/O_2 and I2/pyridine systems gave the cyclized product in moderate yield and the trans isomer was obtained as the sole product. On the other hand, a similar cyclization reaction with antiformin (aq. NaClO) as an oxidant gave the cis isomer as the major product. The reactions of N-tosylaziridines gave the addition products of N-thioacyl-1,3-diamines with low diastereoselectivity but high regioselectivity and in goodto-excellent yields. The use of AlMe3 as an additive improved the efficiency and regioselectivity of the reaction. The stereochemistry of the obtained products was determined by X-ray diffraction.