Asymmetric synthesis of the lactone moiety of mevinic acid
作者:Mark Lautens、Shihong Ma、Adrian Yee
DOI:10.1016/0040-4039(95)00792-b
日期:1995.6
Nickel catalyzed reductive ring-opening of oxabicyclic[3.2.1] compound 3 and enzymatic acetylation of cycloheptenol 4 were used as key steps to prepare the (+)-enantiomer of a derivative of mevinicacidlactone.
Synthesis of Cyclohexenols and Cycloheptenols via the Regioselective Reductive Ring Opening of Oxabicyclic Compounds
作者:Mark Lautens、Shihong Ma、Pauline Chiu
DOI:10.1021/ja964361j
日期:1997.7.1
The reductive ring opening of oxabicycliccompounds has been achieved. While RMgBr/MgBr2 works in a few limited substrates, diisobutylaluminum hydride reacts with oxabicyclic[3.2.1]- and -[2.2.1]alkenes to provide cycloheptenols and cyclohexenols in good yield and in some cases in good regioselectivity. With some substrates further reduction of the alkene was observed which led us to examine transition
Identification and biosynthesis of tropone derivatives and sulfur volatiles produced by bacteria of the marine Roseobacter clade
作者:Verena Thiel、Thorsten Brinkhoff、Jeroen S. Dickschat、Susanne Wickel、Jörg Grunenberg、Irene Wagner-Döbler、Meinhard Simon、Stefan Schulz
DOI:10.1039/b909133e
日期:——
Bacteria of the Roseobacter clade are abundant marine bacteria and are important contributors to the global sulfur cycle. The volatiles produced by two of its members, Phaeobacter gallaeciensis and Oceanibulbus indolifex, were analyzed to investigate whether the released compounds are derived from sulfur metabolism, and which biosynthetic pathways are involved in their formation. Both bacteria emitted different sulfides and thioesters, including new natural compounds such as S-methyl phenylethanethioate (16) and butyl methanesulfonate (21). The S-methyl alkanoates were identified by comparison with standards that were synthesized from the respective methyl alkanoates by a new method using an easily prepared aluminium/sulfur reagent. Phaeobacter gallaeciensis is also able to produce tropone (37) in large amounts. Its biosynthesis was investigated by various feeding experiments, showing that 37 is formed via a deviation of the phenylacetate catabolism. The unstable tropone hydrate 42 was identified as an intermediate of the tropone biosynthesis that was also released together with tropolone (38).
Asymmetric induction into meso-1,3-diacetoxy-5-cycloheptene 4 by PFL-catalyzed hydrolysis afforded monoacetate (1S,3R)-5 of 96% enantiomeric excess (e.e.), which was converted into a synthetic equivalent 14 of the delta-lactone moiety in mevinic acid derivatives. (C) 1997 Published by Elsevier Science Ltd.
Palladium(0)-Mediated Desymmetrization of Meso Tetraols: An Approach to the C3−C17 Bis-oxane Segment of Phorboxazoles A and B
作者:Brian S. Lucas、Steven D. Burke
DOI:10.1021/ol0354775
日期:2003.10.1
[GRAPHICS]meso-Tetraol bis(allylic acetates) 2 and 5 were synthesized via two-directional chain elongation. A palladium-mediated, ligand-controlled desymmetrization provided the desired bis-oxanes in greater than 98% ee. Bis-oxanes 1 and 4 represent potential synthetic intermediates for the C3-C17 subunits of phorboxazoles A and B.