Patent ID: 7365212

Claim:
A process for in situ preparation of a chiral compound from an oxazaborolidine-borane complex, comprising the following steps: 1) adding to a suspension of a metal borohydride defined by formula (I): MBH 4 (I) in which: M a metal ion is selected from the group consisting of sodium, potassium, lithium, and zinc: a) a Lewis base of general formula (II) below: R 1 -A-(R 2 ) n (II) in which: R 1 and R 2 , which are identical or different, are selected from the group consisting of an hydrogen atom, an optionally substituted, linear alkyl, an optionally substituted branched alkyl, an optionally substituted aryl, an alkylaryl, a C 4 -C 7 cycloalkyl, and R 1 and R 2 can together form a C 1 -C 7 alkyl chain or an optionally substituted C 2 -C 7 carbocycle; n is equal to 1 or 2; and A is an atom selected from the group consisting of a nitrogen, oxygen, sulfur and phosphorus; and b) an inorganic acid ester of general formula (III) below: R 3 —X (III) in which: X is selected from the group consisting of a sulfonyloxy ester group (—OS(O) 2 OR 4 ), a sulfonate (—OS(O)R 5 ) and a sulfite (—OS(O)OR 5 ); and R 3 , R 4 and R 5 , which are identical or different, are selected from the group consisting of a linear or branched alkyl, said alkyl being optionally substituted by a substituent selected from the group consisting of a halogen atom, an aryl, a heterocycle, a heteroaryl, an alkoxy group, an alkylthio group, an alkylaryl group a C 4 -C 7 cycloalkyl, and R 4 and R 5 together are selected from a C 1 -C 7 alkyl chain and an optionally substituted C 1 -C 7 carbocycle; 2) and then, adding to the product obtained after step 1 an optically active amino alcohol of general formula (IV) below: in which: R 6 is selected from the group consisting of a hydrogen atom, a linear or branched C 1-8 lower alkyl group; a C 1-15 arylalkyl group, and a C 1-15 arylalkyl group substituted by a substituent selected from the group consisting of C1-C5 alkyl and C 1-5 alkoxy; R 7 , R 8 , R 9 , R 10 , R 11 and R 12 , which are identical or different, independently are selected from the group consisting of a hydrogen atom, a C 1-8 lower alkyl group, a C 6-12 aryl group, an aryl group substituted by a C 1-5 alkyl; a C 7-12 arylalkyl group, an arylalkyl group substituted by a C 1-5 alkyl, with the proviso that R 6 and R 7 are different; R 6 and R 7 , or R 7 and R 11 , or R 8 and R 9 , or R 10 and R 11 together can form a C 3-6 lower alkylene group, a substituted C 3-6 lower alkylene group, R 8 and R 9 together can form an alkylene group that is optionally substituted or fused with a benzene ring; n is equal to 0, 1, 2 or 3; and at least one of C 1 , C 2 and C 3 is an asymmetric carbon atom, thereby obtaining said chiral compound.