Natural product synthesis from (8aR)- and (8aS)-bicyclofarnesols: synthesis of (+)-wiedendiol A, (+)-norsesterterpene diene ester and (−)-subersic acid

Chemoenzymatic Synthesis of (+)-.ALPHA.-Polypodatetraene and Methyl (5R,10R,13R)-Labda-8-en-15-oate

“…1 H-NMR spectra were recorded on a JEOL EX 400 spectrometer. Spectra were taken with 5-10% (w/v) solution in CDCl 3 with Me 4 Si as an internal reference. The mass spectra, FAB and EI, were obtained with a JEOL JMS-600 H (matrix; glycerol, m-nitrobenzyl alcohol) or a JEOL JMS-AM II 50 spectrometer, respectively.…”

“…The reaction mixture was diluted with brine and extracted with Et 2 O. The organic layer was dried over MgSO 4 and evaporated to give a crude silyl ether (8aS)-8 (14.4 g), which was used for the next reaction without further purification. 2) A mixture of methyltriphenylphosphonium bromide (Ph 3 P ϩ -Me Br Ϫ , 75.0 g, 210 mmol) and sodium amide (NaNH 2 , 8.03 g, 206 mmol) in toluene (500 ml) was refluxed with stirring for 3 h under argon atmosphere.…”

“…The reaction mixture was diluted with H 2 O and extracted with Et 2 O. The organic layer was washed with brine and dried over MgSO 4 . Evaporation of the organic solvent gave a crude oil (8aS)-9, which was chromatographed on silica gel (100 g, n-hexane : AcOEtϭ10 : 1) to give (8aS)-10 (7.05 g, 75% (8aS)-Albicanyl Phenyl Sulfide (12) 1) To a solution of (8aS)-10 (1.00 g, 4.50 mmol) in pyridine (15.0 ml) was added methanesulfonyl chloride (MsCl, 0.620 g, 5.40 mmol) and 4-dimethylaminopyridine (DMAP, 0.060 g, 0.500 mmol) at 0°C, and the whole mixture was stirred for 2 h at rt.…”

“…The reaction mixture was diluted with 2 M aqueous NaOH and extracted with Et 2 O. The organic layer was washed with brine and dried over MgSO 4 (؉)-a a-Polypodatetraene (1) 1) 2.6 M n-butyllithium (n-BuLi) in hexame solution (1.90 ml, 4.90 mmol) was added to a stirred solution of diisopropylamine (0.490 g, 4.80 mmol) in THF (1.50 ml) at Ϫ78°C under an argon atmosphere and the mixture was stirred for 15 min at the same temperature. A solution of (8aS)-13 (0.570 g, 1.60 mmol) in THF (1.50 ml) was added to the above LDA-THF solution and the whole mixture was stirred for 15 min at the same temperature.…”

“…The reaction mixture was diluted with brine and extracted with Et 2 O. The organic layer was dried over MgSO 4 . Evaporation of the organic solvent gave a crude oil, which was chromatographed on silica gel (45.0 g, n-hexane : AcOEtϭ100 : 1) to afford a diastereomeric mixture of (8aS)-14 (0.752 g, 83%) as a colorless oil.…”