Synthesis of fulvicacid (1a) was accomplished by a route involving selective ozonization of 9-propenylpyranobenzopyran (1c), obtained by a regioselective cyclization of the 2-methylsulphinylmethyl 1,3-dione(3c).
Totalsynthesis of fulvic acid (1a) is described. Regioselective cyclization of the enedione (8f), an equivalent of the proposed biogenetic intermediate (5a) for citromycetin (2), gave the pyrone (11a), which led to fulvic acid (1a) by a route involving debenzylation, selective ozonization, and hydration.
Regiopspecific cyclization of the acetal (4g), derived in 5 steps from 2′-benzyloxyacetophenone (3a), gave the pyrone (6a), which was easily converted into 2-methyl-5H-pyrano[3,2-c][1]benzopyran-4-one (1b), the basicskeleton in citromycetin (1a).
乙醛(4g)的区域特异性环化,由2'-苄氧基苯乙酮(3a)分5步产生,得到了吡喃酮(6a),该吡喃酮易于转化为2-甲基-5 H-吡喃并[3,2- c ] [ 1]苯并吡喃-4-酮(1b),是柠檬霉素的基本骨架(1a)。
A New, Total Synthesis of Methylenomycin B Using Organic Sulfur and Phosphorus Reagents
作者:Marian Mikołajczyk、Piotr Bałczewski
DOI:10.1055/s-1984-30937
日期:——
Yamauchi, Masashige; Katayama, Sadamu; Nakashita, Yoshihiko, Journal of the Chemical Society. Perkin transactions I, 1984, # 3, p. 503 - 507