摘要:
A process for the preparation of Phosphodiesterase IV inhibitors is described. The process consists of eight chemical steps involving five isolations to prepare the title compound from readily available isovanillin in 35% overall yield (Scheme 1). The process is highlighted by: a) a highly diastereoselective Michael addition of phenyllithium using (1R, 2S) cis-aminoindanol as a chiral auxiliary, b) highly crystalline intermediates providing for efficient purifications, c) crystallization of the final compound as its CSA salt for excellent enantiomeric purity.
摘要:
The instant invention relates to a compound of the formula: ##STR1## wherein R.sub.a and P are: (a) hydrogen,(b) methyl, or(c) a hydroxy protecting groupand an efficient process for its synthesis characterized by combining a ketoester with an acid and a catalyst at a temperature of from about 0.degree. to about 50.degree. C. and from about 0 to 500 psig to produce the above compound.
摘要:
The 4-acryloxyazetidin-2-ones, which are intermediates in the production of carbapenems and penems, are produced from 4-furanylazetidin-2-ones by electrochemical methods.
摘要:
The 4-acyloxyazetidin-2-ones, which are intermediates in the production of carbapenems and penems, are produced from 4-furanylazetidin-2-ones by a sequential oxidation-reduction-oxidation reaction scheme.
摘要:
A process is described for the stereocontrolled synthesis of (3R,4R)-3-[(1R)-1-hydroxyethyl]-4-benzoyloxyazetidin-2-ones and their derivatives by cycloaddition involving an imine and a ketone, generated from 3(S)-hydroxybutyrate which are useful intermediates in the synthesis of carbapenem antibiotics.
摘要:
This invention relates to the synthesis of a bicyclic ketoester compound of the formula 1 obtained by cyclizing a diazo compound of formula 2: in the presence of a rhodium catalyst. ##STR1## By adding an effective amount of a Lewis acid to the cyclization reaction, the reaction selectively produces the 1-beta methyl isomer, and epimerization of the 1-beta methyl compound to the 1-alpha isomer is minimized.
摘要:
The 4-acyloxyazetidin-2-ones, which are intermediates in the production of carbapenems and penems, are produced from nitrogen deprotected 4-furanylazetidin-2-ones.
摘要:
The 4-acyloxyazetidin-2-ones, which are intermediates in the production of carbapenems and penems, are produced from 4-furanylazetidin-2-ones by singlet oxygen oxidation.