合成路线1

The reaction of 5-bromopyridine-3-carboxylic acid (I) with (COCl)2 and CuI in DMF gives the acyl chloride (II), which is reduced with LiAlH(O-tBu)3 in THF to yield the carbaldehyde (III). The allylation of (III) with the organozinc bromide (IV) in THF affords 1-(5-bromo-3-pyridyl)-3-buten-1-ol (V), which is oxidized with DMP in dichloromethane to provide the corresponding ketone (VI). The enantioselective reduction of (VI) with (+)-B-chlorodiisopinocampheyl borane ((+)-DIP-Cl) in ether gives the (R)-enantiomer (VII), which is treated with Ms-Cl and TEA in dichloromethane to yield the mesylate (VIII). The reaction of (VIII) with sodium azide in DMF affords the (S)-azide (IX), which is finally submitted to a reductive cyclization by means of dicyclohexylborane (Cy2BH) in THF to afford the target 3-bromo-5-(2(S)-pyrrolidinyl)pyridine (X) intermediate (see scheme no. 22999801a, intermediate (VI)).