Hendrik Andres

Tritium and deuterium labelling studies of alkali metal borohydrides and their application to simple reductions

Simple and facile syntheses of highly deuterated and tritiated LiBH 4 , NaBH 4 and KBH 4 were achieved by hydrogen isotope exchange with deuterium or tritium gas at elevated temperatures. The exchange products were characterized by boron, proton and deuterium or tritium NMR spectroscopy. The extent of isotope ( 2 H or 3 H) incorporation was calculated from the patterns of 11 B NMR spectra. Several samples of tritiated NaBH 4 were treated with BF 3 -Et 2 O to produce tritiated borane-THF complex, which is an electrophilic reducing agent. The utility of both the borohydride reagents and borane-THF complex in labelling reactions was confirmed by exemplary reductions leading to specifically labelled products. The extent and orientation of labelling in the reduction products was assessed by a combination of radio-HPLC analysis, 1 H, 2 H or 3 H NMR and mass spectrometry.

PREPARATION AND USE OF LITHIUM TRITIDE AND LITHIUM TRIMETHOXYBOROTRITIDE

Abstract Two new tritide reducing agents, Li3H and Li(CH3O)3B3H, have been prepared at the carrier-free level and used to reduce 2-naphthaldehyde to tritiated β-naphthalene methanol, to produce C3H3OR, and to synthesize a methyl-tritiated secondary amine.

Preparation and Use of Tritiated Schwartz' Reagent (ZrCp2Cl3H)

Abstract Treatment of Li3H with ZrCp2Cl2 in THF affords ZrCp2Cl3H. By the action of ZrCp2Cl3H on an acetylene, it is possible to stereo- and regioselectively introduce tritium into the vinylic position, a site which has often proved to be metabolically stable in complex molecules. In addition, ZrCp2Cl3H may be used to regioselectively label olefins with tritium.

Preparation and use of LiEt3BT and LiAlT4 at maximum specific activity

Carrier-free LiEt3BT and LiAlT4 have been generated and used to reduce methyl 2-naphthoate to 2-(hydroxymethyl)naphthalene containing two tritium atoms per molecule.

Synthesis and NMR characterization of tri-n-butyltin tritide

Tri-n-butyltin tritide, a potentially versatile tritiation reagent, is synthesized at maximum specific radioactivity and characterized by 1H, 3H and 119Sn NMR techniques.