Radikalische Cyclisierung von Dienen, VI. Substratkontrollierte asymmetrische Synthese von (3aS,6aR)-(+)-3,3a,6,6a-Tetrahydro-2H-cyclopenta[b]furan-2-on

✍ Scribed by Weinges, Klaus ;Schwarz, Georg

• Publisher: John Wiley and Sons
• Year: 1993
• Tongue: English
• Weight: 468 KB
• Volume: 1993
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.1993199301128

✦ Synopsis

Radical‐Type Cyclization of Dienes, VI. – Substrate‐Controlled Asymmetric Synthesis of (3a__S__,6a__R__)‐(+)‐3,3a,6,6a‐Tetrahydro‐2__H__‐cyclopenta[b]furan‐2‐one

(R)‐(−)‐Carvone (1) was converted via straightforward reactions into 10‐hydroxycarvone (4) which was cyclized to 5 via the mercury‐mediated free‐radical method. Periodate cleavage of 5 yields the bicyclic dione 6. Regio‐ and stereoselective reduction of 6 with lithium tri(tert‐butyloxy)hydridoaluminate results in 7 (80% yield). 7 was directly converted into γ‐lactone 8 via Baeyer‐Villiger oxidation. Saponification of 8 to 9, mesylation of 9 to 10 followed by elimination of methanesulfonic acid yield enantiomerically pure (3a__S__,6a__R__)‐(+)‐3,3a,6,6a‐Tetrahydro‐2__H__‐cyclopenta[b]furan‐2‐one (11). The synthesis can be carried out with readily available, and economical, (S)‐(+)‐carvone to yield ent‐11.