NOVELTY - Preparing (p1) saxagliptin comprises reacting substituted 2-(3-oxy-adamantan-1-yl)-acetoxy compounds (III) with alkali metal azide in the presence of a phase transfer catalyst, treating the formed product with chiral reagent, hydrolysis of the resulting product by employing mineral acid, reacting the formed product with (1S,3S,5S)-2-aza-bicyclo(3.1.0)hexane-3-carboxylic acid amide in the presence of a coupling reagent and coupling additives, dehydrating the resulting product in the presence of a dehydrating reagent and base, and reducing the formed product in the presence of a metal catalyst.    USE - The process is useful for preparing saxagliptin (claimed) which is used for treating type-2 diabetes. No biological data given.    ADVANTAGE - The process is environment friendly and cost effective.    DETAILED DESCRIPTION - Preparing (p1) saxagliptin comprises (a1) reacting substituted 2-(3-oxy-adamantan-1-yl)-acetoxy compounds of formula (III) or its acid addition salt with alkali metal azide in the presence of a phase transfer catalyst to obtain substituted 2-azido-2-(3-oxy-adamantan-1-yl)-acetoxy compounds of formula (IV) or its acid addition salt, (b1) treating (IV) with chiral reagent to obtain substituted (S)-2-azido-2-(3-oxy-adamantan-1-yl)-acetoxy compounds of formula (V), (c1) hydrolysis of (V) by employing mineral acid to obtain substituted (S)-2-azido-2-(3-oxy-adamantan-1-yl)-acetoxy compounds of formula (VI), (d1) reacting (VI) with the (1S,3S,5S)-2-aza-bicyclo(3.1.0)hexane-3-carboxylic acid amide or its acid addition salt in the presence of a coupling reagent and coupling additives to obtain substituted 3-((S)-1-azido-2-((1S,3S,5S)-3-carbamoyl-2-aza-bicyclo(3.1.0)hex-2-yl)-2-oxo-ethyl)-adamantan-1-yloxy compounds of formula (VII) or its acid addition salt, (e1) dehydrating (VII) or its acid addition salt in the presence of a dehydrating reagent and base to obtain substituted 3-((S)-1-azido-2-((1S,3S,5S)-3-cyano-2-aza-bicyclo(3.1.0)hex-2-yl)-2-oxo-ethyl)-adamantan-1-yloxy compounds of formula (VIII) or its acid addition salts, and (f1) reducing (VIII) or its acid addition salt in the presence of a metal catalyst to obtain substituted 3-((S)-1-amino-2-((1S,3S,5S)-3-cyano-2-aza-bicyclo(3.1.0)hex-2-yl)-2-oxo-ethyl)-adamantan-1-yloxy compounds of formula (IX) or its acid addition salt.    R1a, R1b = 1-6C alkyl (optionally substituted);    A1a = chiral reagent; and    L1a = halo or leaving group.    INDEPENDENT CLAIMS are also included for:    (1) preparing (IV) or its acid addition salt comprising the step (a1) as above per se;    (2) preparing (VI) or its acid addition salt comprising the steps (b1) and (c1) as above per se;    (3) preparing (VIII) comprising the steps (d1) and (e1) as above per se;    (4) preparing saxagliptin comprising the step (f1) as above per se;    (5) preparing (p2) saxagliptin comprising: (a2) treating (III) or its acid addition salt with aryl amine of formula (P1a-CH2-NH2) to obtain substituted 2-amino-2-(3-oxy-adamantan-1-yl)-acetoxy compounds of formula (IV-a) or its acid addition salt; (b2) treating (IV-a) with chiral reagent to obtain substituted (S)-2-amino-2-(3-hydroxy-adamantan-1-yl)-acetoxy compounds of formula (V-a); (c2) hydrolysis of (V-a) in the presence of mineral acid to obtain substituted (S)-2-amino-2-(3-hydroxy-adamantan-1-yl)-acetoxy compounds of formula (VI-a); (d2) reacting (VI-a) or its acid addition salt with (1S,3S,5S)-2-aza-bicyclo(3.1.0)hexane-3-carboxylic acid amide or its acid addition salt in the presence of a coupling reagent and coupling additives to obtain substituted 3-((S)-1-amino-2-((1S,3S,5S)-3-carbamoyl-2-aza-bicyclo(3.1.0)hex-2-yl)-2-oxo-ethyl)-adamantan-1-yloxy compounds of formula (VII-a) or its acid addition salt; (e2) treating (VII-a) or its acid addition salt with dehydrating agent in the presence of a base to obtain substituted 3-((S)-1-amino-2-((1S,3S,5S)-3-cyano-2-aza-bicyclo(3.1.0)hex-2-yl)-2-oxo-ethyl)-adamantan-1-yloxy compounds of formula (VIII-a) or its acid addition salts; and (f2) catalytically reducing (VIII-a) or its acid addition salt in the presence of metal catalyst to obtain (IX) or its acid addition salts;    (6) preparing (IV-a) or its acid addition salt comprising the step (a2) as above per se;    (7) preparing (VI-a) or its acid addition salt comprising the steps (b2) and (c2) as above per se;    (8) preparing (VIII-a) or its acid addition salt comprising the steps (d2) and (e2) as above per se;    (9) substituted 2-azido-2-(3-oxy-adamantan-1-yl)-acetoxy compounds (IV) or its acid addition salt;    (10) substituted (S)-2-azido-2-(3-oxy-adamantan-1-yl)-acetoxy compounds (VI) or its acid addition salt;    (11) substituted 3-((S)-1-azido-2-((1S,3S,5S)-3-carbamoyl-2-aza-bicyclo(3.1.0)hex-2-yl)-2-oxo-ethyl)-adamantan-1-yloxy compounds (VII) or its acid addition salt;    (12) substituted 3-((S)-1-azido-2-((1S,3S,5S)-3-cyano-2-aza-bicyclo(3.1.0)hex-2-yl)-2-oxo-ethyl)-adamantan-1-yloxy compounds (VIII) or its acid addition salts;    (13) substituted 2-amino-2-(3-oxy-adamantan-1-yl)-acetoxy compounds (IV-a) or its acid addition salts;    (14) substituted 3-((S)-1-amino-2-((1S,3S,5S)-3-carbamoyl-2-aza-bicyclo(3.1.0)hex-2-yl)-2-oxo-ethyl)-adamantan-1-yloxy compounds (VII-a) or its acid addition salt;    (15) substituted 3-((S)-1-amino-2-((1S,3S,5S)-3-cyano-2-aza-bicyclo(3.1.0)hex-2-yl)-2-oxo-ethyl)-adamantan-1-yloxy (VIII-a) or its acid addition salt;    (16) preparing (p3) saxagliptin;    (17) preparing (VIII) comprising the steps (b3) and (c3) as above per se; and    (18) preparing (p4) saxagliptin.    P1a = -NCH2PH