Abstract: The invention provides process for preparing antibody-drug conjugates, preferably trastuzumab maytansinoid conjugate linked via non-cleavable linker comprising performing the conjugation reaction at lower temperature than ambient and/or at lower pH condition than neutrality. The process according to the present invention comprises conjugating the linker modified antibody with cytotoxic drug, preferably the SMCC-modified trastuzumab with a cytotoxic drug, preferably maytansinoid at a temperature lower than 20° C. and at a pH lower than 6.0, and thereby preparing an antibody-drug conjugate, preferably trastuzumab maytansinoid conjugate, T-DM1.

Abstract: The present invention provides a process for production of optically pure quinuclidinol of formula-(I) by reduction of quinuclidinone of formula-(II) in presence of suitable oxidoreductase enzyme derived from Saccharomyces species. Formula (II, I) Moreover, the present enzyme works in presence of cofactor NADP where the cofactor is regenerated by suitable system. The present invention also provides a recombinant vector containing genes co expressing suitable polypeptides having oxido-reductase activity and polypeptide having capacity to regenerate the co-factor. The said vector is transformed in suitable host cell.

Abstract: The invention provides a process for preparing 3-hydroxy-1-(3-(trifluoromethyl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)-4-(2,4,5-trifluorophenyl)butan-1-one (Formula I), into its racemic (R/S) form or any of its optically active (S) or (R) forms or enantiomeric excess mixture of any of the forms comprising: a) reacting 4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-one of formula (III) with a suitable oxidoreductase enzymes or its suitable variants in the presence of suitable conditions and co-factor; and b) isolating 3-hydroxy-1-(3-(trifluoromethyl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)-4-(2,4,5-trifluorophenyl)butan-1-one, into its racemic (R/S) form or any of its optically active (S) or (R) forms or enantiomeric excess mixture of any of the forms.