We have developed a new, efficient method for the synthesis of benzylphosphonate and benzylphosphonothioate diesters via a palladium(0)-catalyzed cross-coupling reaction between benzyl halides and H-phosphonate or H-phosphonothioate diesters, using Pd 2 (dba) 3 (CHCl 3 ) as a palladium source and Xantphos as a supporting ligand. Some mechanistic aspects of these reactions were investigated using 31 P NMR spectroscopy.

A number of model structures of the CalA suggested by comparative modeling were tested by site-directed mutagenesis. Enzyme variants were created where amino acids predicted to play key roles for the lipase activity in the different models were replaced by an inert amino acid (alanine). The results from activity measurements of the overproduced and purified mutant enzymes indicate a structure where the active site consists of amino acid residues Ser184, His366, and Asp334 and in which there is no lid. This model can be used for future targeted modifications of the enzyme to obtain new substrate acceptance, better thermostability, and higher enantioselectivity.

Prediction of the Candida antarctica Lipase A Protein Structure by Comparative Modeling and Site-Directed Mutagenesis. -(KASRAYAN, A.; BOCOLA, M.; SANDSTROEM, A. G.; LAVEN, G.; BAECKVALL*, J.-E.; ChemBioChem 8 (2007) 12, 1409-1415; Dep. Org. Chem., Arrhenius Lab., Univ. Stockholm, S-106 91 Stockholm, Swed.; Eng.) -Lindner 44-197

A new, efficient method for the synthesis of benzylphosphonate diesters via a palladium(0)-catalyzed cross-coupling reaction between benzyl halides and H-phosphonate diesters, using Pd(OAc) 2 as a palladium source and Xantphos as a supporting ligand, has been developed.

Organo-phosphorus compounds S 0080Palladium (0)-Catalyzed Benzylation of H-Phosphonate Diesters: An Efficient Entry to Benzylphosphonates. -Similar reactions with dinucleoside H-phosphonates show that the reaction most likely proceeds with retention of configuration at the phosphorus center. -(LAVEN, G.; STAWINSKI*, J.; Synlett 2009, 2, 225-228; Dep. Org. Chem., Arrhenius Lab., Univ. Stockholm, S-106 91 Stockholm, Swed.; Eng.) -Mais 22-173