Catalytic Michael/Ring-Closure Reaction of α,β-Unsaturated Pyrazoleamides with Amidomalonates: Asymmetric Synthesis of (?)-Paroxetine
A highly enantioselective tandem Michael/ring-closure reaction of α,β-unsaturated pyrazoleamides and amidomalonates has been accomplished in the presence of a chiral N,N′-dioxide–Yb(OTf)3complex (Tf: trifluoromethanesulfonyl) to give various substituted chiral glutarimides with high yields and diastereo- and enantioselectivities. Moreover, this methodology could be used for gram-scale manipulation and was successfully applied to the synthesis of (?)-paroxetine. Further nonlinear and HRMS studies revealed that the real catalytically active species was a monomeric L-PMe2–Yb3+complex. A plausible transition state was proposed to explain the origin of the asymmetric induction.
PROCESS FOR STEREOSPECIFIC HYDROLYSIS OF PIPERIDINEDIONE DERIVATIVES
A process for stereospecifically hydrolysing a mixture of the (+) and (-) isomers of a compound of formula (II), in which R is C1-6 alkyl; using a carboxyl esterase enzyme, (i) to form a compound of formula (IIIA), and thereafter separating the resulting compound of formula (IIIA) from the remaining (-) isomer of formula (II); or (ii) to form a compound of formula (IIIB) and thereafter separating the resulting compound of formula (IIIB) from the remaining (+) isomer of formula (II).
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(2008/06/13)
Process for the preparation of aryl-piperidine carbinols
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(2008/06/13)
Process for preparing aryl-piperidine carbinols and novel intermediates used in the process
A process is disclosed for the preparation of a compound of formula (I): STR1 wherein Ar is aryl or substituted aryl and R3 is hydrogen, alkyl or aralkyl, which process comprises reducing a compound of formula (II): STR2 wherein Ar and R3 are as defined with respect to formula (I) and R4 is alkyl. Compounds of formula (I) are useful as chemical intermediates.
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(2008/06/13)
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