Reactions of 2,3,19-trihydroxyurs-12-triterpenoids: Pinacol rearrangement of methyl 2α,3β,19α-trihydroxyurs-12-en-28-oate

✍ Scribed by L.A Tapondjou; F.N. Ngounou; D. Lontsi; B.L. Sondengam; J.D. Connolly

• Book ID: 104208319
• Publisher: Elsevier Science
• Year: 1998
• Tongue: French
• Weight: 495 KB
• Volume: 54
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(97)10418-5

✦ Synopsis

Pinacol rearrangement of the title group of compounds has been investigated and the structures of the adducts elucidated. Three different A-ring carbonylated compounds were obtained, two of which (2 and 4) remained with a six-member ring as in the starting material 1, and the third one (3) with a cyclopentanic ring as a consequence of the A-ring contraction. In addition to normal pinacol rearrangement of ring A, the reaction led to the isomerization of Al2 double bond in all of the products (2-4) with compounds 2 and 3 as dienic triterpenes, and compound 4 with an E-ring y-lactonic system.