Total synthesis of 2-azaestratrienes

Abstract

The total synthesis of (±)-2-azaestradiol 3-methyl ether (15) as well as its 11/3-methyl homologue 28 is described. This work necessitated the development of a synthesis of 6-methoxy-7-aza-1 -tetralone (7), a heretofore unknown compound. In the course of the preparation of this tetralone, a novel -pyridone synthesis was developed. The chemical reduction of the 8,9 double bond in each series was accompanied by destruction of the methoxypyridine A ring. Rearomatization of the dihydropyridines 14 and 27 with DDQ regenerated the methoxypyridine nucleus and gave the desired products. A by-product of the DDQ reaction in the 11/3-methyl series was identified as (±)-9£hydroxy-2-azaestradiol 3-methyl ether (29).

Tentative molecular mechanism for germination stimulation of Striga and Orobanche seeds by strigol and its synthetic analogs

“…), 5.89 (d, J = 7.5 Hz, H8b), 7.00-7.53 (m, 6 Ar ), 7.60 (d, J = 2.5 Hz, =CHO), 7.82 (d, J = 8 Hz, 2 Ar H); IR (KBr) v 1750 (0=0, 18). For the preparation of 18 from potassium salt 16 (Mangnus et al, 1992a) and 3-chloro-5,5-dimethylcyclohex-2-en-l-one (Chorvat et al, 1978) the procedure described for 17 was followed; however, the solvent, tetrahydrofuran, was replaced by dimethylformamide. The crude product was purified by flash chromatography [silica gel, petroleum ether/ethyl acetate (2:1)] to give 18 as a white solid (yield 30%).…”

A total synthesis of 4-cyano-1,3-dimethoxy-2-azaestra-1,3,5(10)-trien-17β-ol and its configuration assignment

“…The crucial step in the total synthesis of estradiol-3-methyl ether analogue (6~a) is the trans-reduction oT the 8,9-double bond. Birch reduction failed to yield the required product since the heteroaromatic nucleus was labile to it (Charat et al 1978). The 8,9-double bond in 4 was herLce isomerisedto the 9(11)position by refluxing with methanolic hydrochloric acid for 16 hr.…”