Enzymatic Resolution of Aminocyclopentenols as Precursors to d- and l-Carbocyclic Nucleosides
摘要:
Racemic cis-4-aminocyclopent-2-en-1-ols were synthesized in three steps utilizing hetero Diels-Alder chemistry. Starting from suitably protected hydroxylamines, oxidization with sodium periodate and trapping with cyclopentadiene afforded cycloadducts (+/-)-5a-d. The N-O bond of the cycloadducts was reduced with Mo(CO)(6) to afford (+/-)-cis-4-aminocyclopent-2-en-1-ols (+/-)-6a-d. These compounds, or their corresponding acetates, were kinetically resolved by enzymatic acetylation or hydrolysis, respectively. Enzymatic acetylation of cis-N-(benzylcarbamoyl)-4-aminocyclopent-2-enol [(+/-)-6a] with Candida antarctica B lipase and Pseudomonas species lipase gave the corresponding acetate (-)-7a in 90% and 92% ee, respectively, after 40% conversion. Enzymatic hydrolysis of cis-N-acetyl-4-aminocyclopent-2-enol 1-O-acetate (+/-)-7d with electric eel acetylcholine esterase was successful in providing both cis-N-acetyl-4-aminocyclopent-2-enols (+)ed and (+)-7d in 92% ee (99% ee after a single recrystallization) after 40% conversion. Further synthetic transformations of these resolved synthetic building blocks and derivatives are also reported.
1,2,3-triazolo[4,5-d]pyrimidines as P2T receptor antagonists
申请人:AstraZeneca UK Limited
公开号:US06251910B1
公开(公告)日:2001-06-26
Compounds of formula having the following stereochemistry
wherein R, R1, R2, R3 and R4 are as defined in the specification. The compounds are useful as P2T receptor antagonists.
The invention provides novel 1,2,3-triazolo[4,5-d]pyrimidine compounds, their use as medicaments, compositions containing them and processes for their preparation.
Diastereoselective [4+2] Cycloadditions of Acyl Nitroso Compounds
作者:Stephen F. Martin、Michael Hartmann、John A. Josey
DOI:10.1016/s0040-4039(00)92508-5
日期:1992.6
A highly diastereoselective route to unsaturated amino alcohol derivatives has been developed that features the [4+2] cycloaddition of chiral acyl nitrosocompounds to a variety of conjugated dienes; a useful oxidative method for generating acyl nitrosocompounds from the corresponding hydroxamic acids under very mild conditions was also discovered.