example 1b c and using 2s 4r 5r 1 tert butoxycarbonyl 4 5 dimethyl 2 hydroxymethylpyrrolidine 2s 4r 5r 4 5 dimethyl 2 hydroxymethylpyrrolidine hydrochloride is obtained in the same manner as in example 1b d and using 2s 4r 5r 4 5 dimethyl 2 hydroxymethylpyrrolidine hydrochloride 3 2s 4r 5r 4 5 dimethyl 2 hydroxymethylpyrrolidin 1 yl propionitrile is obtained in the same manner as in example 1b e and using 3 2s 4r 5r 4 5 dimethyl 2 hydroxymethylpyrrolidin 1 yl propionitrile and n n diethyl 2 3 dimethylbenzamide 3 2 2s 4r 5r 4 5 dimethyl 2 hydroxymethylpyrrolidin 1 yl ethyl 5 methyl 2h isoquinolin 1 one is obtained in the same manner as in the method described in tetrahedron lett vol 34 no 3 pp 537 540 1993 ethyl 2r 4s 5s 4 5 dimethylpyrrolidine 2 carboxylate is obtained in the same manner as in example 3b and using ethyl 2r 4s 5s 4 5 dimethylpyrrolidine 2 carboxylate 3 2 2r 4s 5s 4 5 dimethyl 2 hydroxymethylpyrrolidin 1 yl ethyl 5 methyl 2h isoquinolin 1 one is obtained 2r 4s 4 methylpyrrolidine 2 carboxylic acid described in j chem soc c pp 514 522 1971 is reacted with di tert butyl dicarbonate to give 2r 4s 1 tert butoxycarbonyl 4 methylpyrrolidine 2 carboxylic acid 2r 4s 1 tert butoxycarbonyl 4 methylpyrrolidine 2 carboxylic acid is reacted with methyl iodide in the presence of potassium carbonate in acetonitrile solvent to give methyl 2r 4s 1 tert butoxycarbonyl 4 methylpyrrolidine 2 carboxylate methyl 2r 4s 1 tert butoxycarbonyl 4 methylpyrrolidine 2 carboxylate is reduced with lithium borohydride to give 2r 4s 1 tert.