SYNTHESIS OF 15-DEOXY-16-BETA-ETHOXYBRUCEANTIN AND SYNTHETIC EFFORTS TOWARD BRUCEANTIN

• Published in: Journal of organic chemistry Vol. 59; no. 2; pp. 311 - 323
• Main Authors: CHIU, CKF, GOVINDAN, SV, FUCHS, PL
• Format: Journal Article
• Language: English
• Published: WASHINGTON Amer Chemical Soc 28.01.1994; American Chemical Society
• Subjects: Alicyclic compounds, terpenoids, prostaglandins, steroids; Chemistry; Chemistry, Organic; Exact sciences and technology; Organic chemistry; Physical Sciences; Preparations and properties; Science & Technology; Terpenoids; ALCOHOLS; SUPPORT; ETHERS; QUASSINOIDS; REAGENTS; PROTECTION; ROUTES; CONVERSION; INTERMEDIATE; RING-SYSTEM; Michael addition; Pentacyclic compound; Intramolecular reaction; Ketol; Tetracyclic compound; Tricyclic compound; Oxygen heterocycle; Alkylation; Acetal; Cyclization; Asymmetric reaction; Diterpene; Benzenic compound; Aromatic compound; Primary amine; Enone; Glycol
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo00081a008

Utilization of asymmetric Michael addition leads to chiral phenanthrenone (+)-4 suitable for the synthesis of Bruceantin. The D-ring is assembled by means of an intramolecular alkylation of the bromoacetals 25 while only the axial diastereomer 25ax proceeds smoothly. The formation of the cyanohydrin introduces the C-13 carborxyl group and tandem intramolecular alkylation provides the furan E-ring. The C-11,12 cis-diol 39 is readily transformed to the trans-diol 42 via an unusual Swern-type oxidation/reduction sequence. The C-2,3 olefin proves to be an efficient progenitor for the A-ring diosphenol function which can be introduced at the late stage of the synthesis. 15-Deoxy-16 beta-ethoxybruceantin 3 is accordingly prepared. Attempts to elaborate common intermediates toward the synthesis of bruceantin are described. The presence of an oxygen function at C-15 drastically changes the relative reactivity of the C-2,3 and C-11,12 olefinic bonds.