Chemoenzymatic and electrochemical oxidations in the synthesis of octahydroisoquinolines for conversion to morphine. Relative merits of radical vs. acid-catalyzed cyclizations

✍ Scribed by Mary Ann Endoma; Gabor Butora; Christopher D. Claeboe; Tomas Hudlicky; Khalil A. Abboud

• Book ID: 104258390
• Publisher: Elsevier Science
• Year: 1997
• Tongue: French
• Weight: 244 KB
• Volume: 38
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(97)10384-7

✦ Synopsis

Second-generation stereoselective synthesis of octahydm~uinoliue 3, a potential key intermediate for the projected synthesis of the nattnl enantion3er of morphine, has been accomplished in five steps from areue c/s-diol 8. Electmchemi~ oxidation of 9b furnished 7b, a precursor for the key benzoate-assisted acyl-im~um cyclizatiorL © 1997 Elsevier Science Ltd.

Recently we reported the chemoenzymatic synthesis of ent-morphinan I in dmteen steps from o-bromo-~lmm3c~thylbenzene by sequential radical cyclizations that established the consecutive formation of the C14-C'9 and C12--C13 bonds, respectively, t The reverse order of this particular connective strategy was used by Pinker (radical cycliTAtiofl) ~ and by us lb whereas Grewe, 3 Beyerman, 4 and Rice s'6 relied on forming the C12--C13 bond