Asymmetric endoselective [4+2] heterocycloadditions of styrene dienophiles with chiral benzylidenepyruvic esters. Total synthesis of (−)-O-dimethylsugiresinol

✍ Scribed by Gilles Dujardin; Mickaël Maudet; Eric Brown

• Publisher: Elsevier Science
• Year: 1997
• Tongue: French
• Weight: 217 KB
• Volume: 38
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(97)00144-5

✦ Synopsis

Eu(fod) 3 catalyzed [4+2] heterocycloadditions ofpara-methoxystyrene 7 with esters 8a-f of benzylidenepyruvic acids (deriving from various chiral alcohols) furnished endo adducts 9a-f with variable diastereoselective ratios (from 58/42 to 86/14). Interestingly, the benzylidenepyruvic esters 8g and 8h, deriving from a new chiral vector, the ot-O-silyl ether 6 of (D)-(-)-erythronolactone 5, gave the corresponding endo adducts 9g and 9h with a high diastereoselective ratio (dr -> 95/5). The adduct 9h was used as a precursor in a five-step synthesis of "natural" (-)-dimethylsugiresinol (lb).