Synthesis of 4-deuterated 1,4-DHP derivatives^a.

^aReaction conditions: pyridine substrate (1 equiv.), B₂eg₂ (1.1 equiv.), Cs₂CO₃ (1.1 equiv.), MeOD (22 equiv.), sealed tube, 50 °C for 14 h. Yields of the 1,4-DHP products were determined by ¹H NMR analysis of the reaction mixture using DMSO as the internal standard (isolated yields are shown in parentheses).

^bTHF as the solvent.

^cMeCN as the solvent.

^dMeONa was used instead of Cs₂CO₃.

^eMeOK and 18-crown-6 (1.1 equiv. both) were used instead of Cs₂CO₃.

^fThe reaction was conducted at 65 °C.