L-Threonine was transformed, stereospecifically, to a versatile β-lactam (5a) in 3 steps. This β-lactam was further converted to a key intermediate (25) for the synthesis of thienamycin and its biologically active analogues. Furthermore, the compound 5a was changed to iodides (18 and 23), cyanides (19 and 24), chloromethylketone (26) and aldehydes (30 and 31) which appear to have a latent potential
Enantioselective Epoxidation of Nonconjugated <i>cis</i>-Olefins by Chiral Dioxirane
作者:Christopher P. Burke、Yian Shi
DOI:10.1021/ol901724v
日期:2009.11.19
A variety of nonconjugated cis-olefins has been enantioselectively epoxidized with chiral ketones 2, and up to 92% ee has been obtained. The two prochiral faces of an olefin are likely stereodifferentiated by the relative hydrophobicity of the olefin substituents and/or allylic oxygen functionality.
Preparation of azetidinones via N-protected oxirancecarboxamide
申请人:Schering Corporation
公开号:US04740595A1
公开(公告)日:1988-04-26
A multistep process is disclosed for preparing azetidinone intermediates used in the making penems and carbapenems wherein intermediates containing ##STR1## R' is independently hydrogen or 1, 2 or 3 of lower alkyl or lower alkoxy, preferably hydrogen, wherein R" is methyl, ethyl, a phenyl or alkyl, preferably ethyl, as a readily removable nitrogen protecting group are made.
Novel azetidinones for carbapenems and fragmentation in the allylamine precursor analogue
作者:Natalya K. Selezneva、Zuleykha R. Valiullina、Lidiya S. Khasanova、Fanuza A. Gimalova、Raisa Z. Biglova、Mansur S. Miftakhov
DOI:10.1016/j.mencom.2018.03.005
日期:2018.3
(2R,3R)-N-(3-Methoxy-2,3-dioxopropyl)-N-(4-methoxy-phenyl)-2,3-epoxybutanamide on treatment with strong bases (LDA, LHMDS) gives 3-[(1R)-1-hydroxyethyl]azetidin-2-one derivative, while the N-(3-methoxy-2-methylidene-3-oxo-propyl) analogue undergoes fragmentation.
Investigation of the stereochemistry of the dehydration of the diketide, (3R)-3-hydroxybutyrate to crotonate, in the first chain extension cycle on the aspyrone polyketide synthase in intact cells of Aspergillus melleus
作者:Adam Jacobs、James Staunton
DOI:10.1039/c39950000863
日期:——
When samples of the diketide, (3R)-3-hydroxybutyrate, labelled stereospecifically with deuterium at C-2 in the Re and Si positions, are administered to Aspergillus melleus, and the resulting aspyrone examined by 2H NMR, the (2R-)-[2-2H1]-enantiomer gives a much higher level of incorporation at the expected position which is consistent with a syn elimination mechanism.