Stereoselective synthesis of (22R, 23R, 24S)-3β-hydroxy-5-ene-22,23-dihydroxy-24-methyl-cholestane: A brassinolide intermediate from 16-dehydropregnenolone acetate.

✍ Scribed by Braja G. Hazra; Padmakar L. Joshi; Bharat B. Bahule; Narshinha P. Argade; Vandana S. Pore; Mahendra D. Chordia

• Publisher: Elsevier Science
• Year: 1994
• Tongue: French
• Weight: 760 KB
• Volume: 50
• Category: Article
• ISSN: 0040-4020
• DOI: 10.1016/s0040-4020(01)86968-4

✦ Synopsis

Abstnzck: A new synthesis of the important aldehyde I torn easily available l&Dehydropregnenolone acetate (I6-DPA) in high yield is described. The aidehyde I ip converted to trio1 24, involving a stereaselective generation of all the four chiral centers in the brassinolide side chain. The important features of this synthesis ts sterecspecifx generation of the acetate 14 through ene reaction using three d@erent catalysts as well as regioseIective wittig reaction on the acetoxy aIdehyde 20. Conversion of trio1 24 to brassbwlkie ic known, hence this constitutes a formal total synthesis of brassinolide.

Discovery of a powerful plant growth regulator brassinolide 3 in 1979 by Grove etal' has led the foundation of a new era in the field of phytochemistry. Since then several other brassinosteroids have been