SUMMARYThe syntheses of trans-5-chloro-2,3,3a-l2b-tetrahydro-2-methyl- pyrrole (Org 30526) labelled with 3H are described. 3H-labelled Org 5222 of low specific activity was prepared by a base catalyzed exchange with tritiated water of an amide precursor, 3H-labelled Org 5222 with a high specific activity by a catalytic reductive dehalogenation. 3H-labelled Org 30526 was prepared both by demethylation of 3H-Org 5222 and by catalytic reductive iodination of 11-iodo-Org 30526. l4C-1abelled Org 5222 was synthesized in 6 steps using 14C-sarcosine as starting material. 36C1-labelled Org 5222 was prepared by diazotation reaction in the presence of H3%l.

Be p rid i I [ N-be nzy I -3i so b u toxy -Np he n y I -2 -( pyrrol id i n -1y I ) pro py la m i ne] t ri t ia ted i n the pyrro I id i ne ring by reduction of the 2,5-dihydropyrrol-I -yl analogue with tritium shows a complicated 'Hdecoupled 3H n.m.r. spectrum. With the aid of isotopic fractionation by h.p.1.c. this spectrum could be interpreted as a sum of the spectra of various mono-, di-, and tri-tritiated diastereoisomers. In the case of the (+)-(R)-isomer of bepridil the optical purity could be determined by 3H n.m.r. in the presence of Pirkle's alcohol. Tritium n.m.r. is the method of choice for the determination of the position and distribution of the tritium in labelled compounds.'.' The 'H decoupling which is usually applied simplifies the signals to singlets; for vicinal or geminal ditritiated compounds doublets are obtained which usually appear 0.05-0.1 p.p.m. upfield of the corresponding signals for the monotritiated compounds because of the isotope effect., Bepridil [N-benzyl-3-isobutoxy-N-phenyl-2-(pyrrolidin-1-y1)propylaminef (la) as its monohydrochloride monohydrate is a new anti-anginal drug with calcium antagonistic proper tie^.^ For biological and metabolical studies we synthesized this compound and ( +)-(R)-bepridil (lb) tritiated in the pyrrolidine ring. The n.m.r. spectra obtained for these compounds show very complex multiplets. The analysis of these spectra is described in this paper. * With 'H, no racemization was observed on reduction of compound (2b).

SUMMARYThe stereochemistry of reductive debromination and deiodination of 4-haloprolines and 2-or 7-bromocholesterols with 2H2 catalyzed by Pd was investigated using ' H NMR. The reactions are stereoselective but not stereospecific.

The article describes approaches for the synthesis and analysis of isotopically (

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