Lactones, 2. Synthesis of Enantiomeric Pairs of Lactones with the Pinane or the Fenchane system

✍ Scribed by Paruch, Edyta ;Ciunik, Zbigniew ;Wawrzeńczyk, Czeslaw

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 547 KB
• Volume: 1997
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199719971123

✦ Synopsis

Scheme 1 la, b a,lR b,lS 2a, b a,lR, 3R b,lS, 3s 3a, b a,lR, 3R b,lS, 3 s J (iii) 8 Sa, b 4a, b a, IR, 2S, 6R b, lS, 2 R, 6s a, lR, 2S, 6R b, l S , 2R, 6s Reagents (i) MeC(OEt)3, EtCOzH, 138', 48 h, ii) KOH, EtOH,reflux, (iii) J2, KJ, NaHCO3, Et20, (iv) (n Bu)3SnH, C6Hg

Both myrtenols were subjected to the orthoacetate modification of the Claisen rearrangement. [91[101 The products of this reaction, (+) ester 2a and (-) ester 2b were obtained according to GC (cyclodextrin-B-2,3,6-M-19, 25 m X 0.25 mm X 0.25 pm) as pure (greater than 97%) enantiomers, in a 56% and 62% yield respectively. Their structures were confirmed by the 'H-NMR spectra obtained. The values of coupling constants: J3-H,4-Hp (9.9 Hz), J3.H,4.Ho. (2.5 Hz) and the long distance coupling constant J ~-H ~, ~. H B (1.9 Hz)