Use of 1,3-Dioxin-4-ones and Related Compounds in Synthesis. XLIV. Asymmetric Aldol Reaction of 4-Trimethylsiloxy-6-methylene-1,3-dioxines: Use of Tartaric Acid-Derived (Acyloxy)borane Complex as the Catalyst.
Use of 1,3-Dioxin-4-ones and Related Compounds in Synthesis. XLIV. Asymmetric Aldol Reaction of 4-Trimethylsiloxy-6-methylene-1,3-dioxines: Use of Tartaric Acid-Derived (Acyloxy)borane Complex as the Catalyst.
Use of 1,3-Dioxin-4-ones and Related Compounds in Synthesis. XLIV. Asymmetric Aldol Reaction of 4-Trimethylsiloxy-6-methylene-1,3-dioxines: Use of Tartaric Acid-Derived (Acyloxy)borane Complex as the Catalyst.
A novel enantioselective synthesis of 1, 3-dioxin-4-ones having a 2-hydroxylated alkyl group at the 6-position has been accomplished by chiral tartaric acid-derived acylborane-mediated aldol condensation of the silyl enol ether derived from 6-methyl-derivatives of 1, 3-dioxin-4-one with achiral aldehydes.
Enantioselective Synthesis of Cyclothiazide Analogues: Novel Probes of the Stereospecific Actions of Benzothiadiazines at AMPA-Type Glutamate Receptors
作者:Yuefei Hu、Kelvin A. Yamada、David K. Chalmers、Durga P. Annavajjula、Douglas F. Covey
DOI:10.1021/ja9525317
日期:1996.1.1
The stereospecific interactions of the eight stereoisomers of dihydromethylcyclothiazide, an analogue of cyclothiazide, with AMPA-type glutamate receptors was investigated using electrophysiological methods that measured the ability of each stereoisomer to inhibit AMPA receptor desensitization. The eight stereoisomers were obtained by HPLC separation of four pairs of enantiomerically pure (>95% ee) diastereomers prepared from (1R-exo)-, (1R-endo)-, (1S-exo)-, and (1S-endo)-2-methylbicyclo[2.2.1]heptane-2-carboxaldehyde intermediates. The desensitization process was blocked most potently by [1S-[1 alpha,2 alpha(R*),4 alpha]]-dihydromethylcyclothiazide, one of the stereoisomers prepared from the (1S-endo)-carboxaldehyde. The smallest effects on the desensitization process were found for the four stereoisomers prepared from the (1R-exo)- and (1R-endo)-carboxaldehydes. Significant differences in the ability to inhibit desensitization were observed between all diastereomer pairs except those prepared from the (1S-exo)-carboxaldehyde.