Methylation-ring opening of 3,3-disubstituted 2,3-epoxy alcohols. Synthesis of chiral quaternary fragments for assembly of briaran diterpenes
摘要:
Two chiral quaternary carbon-containing fragments suitable for elaboration to the briaran diterpenes were obtained by regioselective methylation of functionalized 3,3-disubstituted 2,3-epoxy-1-ols. The factors which favor methylation at the more hindered position of a trisubstituted 2.3-epoxy alcohol were determined. (C) 1997 Elsevier Science Ltd.
Gas-phase fragmentation of γ-lactone derivatives by electrospray ionization tandem mass spectrometry
作者:Antonio E. M. Crotti、Erika S. Bronze-Uhle、Paulo G. B. D. Nascimento、Paulo M. Donate、Sérgio E. Galembeck、Ricardo Vessecchi、Norberto P. Lopes
DOI:10.1002/jms.1682
日期:——
Fragmentation reactions of β‐hydroxymethyl‐, β‐acetoxymethyl‐ and β‐benzyloxymethyl‐butenolides and the corresponding γ‐butyrolactones were investigated by electrospray ionization tandem massspectrometry (ESI‐MS/MS) using collision‐induced dissociation (CID). This study revealed that loss of H2O [M + H −18]+ is the main fragmentation process for β‐hydroxymethylbutenolide (1) and β‐hydroxymethyl‐γ‐butyrolactone
Bakers' yeast reduction of 3-benzyloxymethylbutenolide gave (S)-3-benzyloxymethylbutanolide, and its transformation to Factor-I, the autoregulator of Streptomyces viridocchromogenes, was examined.