Synthesis of [allyl‐2,3‐3H]‐MN‐9201

Key step of the synthesis of calcium antagonist MN-9201 was the cyclizing addition of the allyl-3-amino-crotonate onto methyl 2-[(3-nitrophenyl) methylene]-3-oxobutanoate. It was then used to synthesize [Allyl-2,3-3H]-MN-9201 by the catalytic addition of tritium gas. Its radiochemical purity and specific activity were 98% and 2.1 TBq/mmol, respectively. © 1998 John Wiley & Sons, Ltd.