unsymmetric α,β,α′,β′-unsaturated ketones (10a—f) were designed for the regioselective 1,4-addition reaction with alkenylboronic acids (4a—j). Since they have substituents to disturb the 1,4-addition reaction on only one double bond, the alkenylboronic acids reacted with them from only one side to selectively provide γ,δ,α′,β′-unsaturated ketones (11a—q). Further transformations of the resulting γ,δ,α′,β′-unsaturated
Chemoenzymatic and enantiodivergent routes to 1,2-ring-fused bicyclo[2.2.2]octane and related tricyclic frameworks
作者:Kerrie A. B. Austin、Jon D. Elsworth、Martin G. Banwell、Anthony C. Willis
DOI:10.1039/b921600f
日期:——
New and simple protocols are described for the conversion of the enzymatically-derived and enantiomerically pure cis-1,2-dihydrocatechol 7 (X = I) and its 6-methylated derivative into either antipodal form of compounds embodying the tricyclic frameworks of terpenoids 1–6. Key steps include intramolecular Diels–Alder (IMDA) and (in some cases) singlet or triplet-based photochemical processes.
Approaches to the Neurotrophically Active Natural Product 11-O-Debenzoyltashironin: A Chemoenzymatic Total Synthesis of the Structurally Related Sesquiterpene Khusiol
作者:Mukesh K. Sharma、Martin G. Banwell、Anthony C. Willis、A. David Rae
DOI:10.1002/asia.201100913
日期:2012.4
cis‐1,2‐dihydrocatechol 4 has been converted, over 16 steps including one involving an intramolecular Diels–Alder reaction, into the sesquiterpenoid naturalproductkhusiol (3), which is structurallyrelated to the neurite outgrowth‐promoting naturalproduct 11‐O‐debenzoyltashironin (1).
Addition of nitrile oxides to olefins. Synthesis of dihydrojasmone and starting material for prostanoids. A novel route to pyrroles
作者:S.K. Mukerji、K.K. Sharma、K.B.G. Torssell
DOI:10.1016/s0040-4020(01)91944-1
日期:——
Routes to dihydrojasmone and γ-keto-aldehydes and an alternative procedure for a key intermediate in our prostaglandin synthesis are described. 2-Isoxazolines are useful intermediates for a preparation of a variety of classes of compounds. A novel route to pyrroles is established.
The target molecule 1b has been prepared by a new methodology via silyl nitronates and 2-isoxazolines. Since 1a was converted earlier into PGE1 our approach constitutes a novel entrance to prostaglandins.