Original scientific paper

Synthesis, Conformational Studies and Enantioselective Homogeneous Catalytic Hydrogenation with CRC-PHOS, and Some Congeners

G. Comisso ; CRC, Chemical Research Company, 33048 San Giovanni al Natisone (UD), Italy
A . Sega ; CRC, Chemical Research Company, 33048 San Giovanni al Natisone (UD), Italy
V. Šunjić ; CRC, Chemical Research Company, 33048 San Giovanni al Natisone (UD), Italy
A. Lisini ; Universitd degli Studi, Istituto di Chimica, Piazza Europa, Trieste, Italy

Abstract

The lactone of (1S,3R)-1-hydroxy-1-diphenylphosphino metyl-
2,2,3-trimethylcyclopentan-3-carboxylic acid (8, CRC-PHOS),
and (1R,3R)-bis(diphenylphosphinoxymethyl)-2,2,3-trimethylcyclopentane
(16), were prepared starting from ( + )-camphanic and (-)-
isocamphoric acid, respectively. Their complex salts [Rh(norbornadiene)
lactone of (1S,3R)-1-hydroxy-1-diphenylphosphinomethyl-
2,2,3-trimethylcyclopentan-3-carboxylic acid] perchlorate (27), and
[Rh(norbornadiene (1R,3R)-1,2,2-trimethyl-1,3-bis ( diphenylphosphinoxymethyl)
cyclopentane)] perchlorate (28) were isolated and their
catalytic and enantioselective ability tested on some model prochiral
carboxylic acids. The asymetric bias did not exceed 35°/o e. e. in
either case. Attepmts at preparation of the diphosphine congener
of 16, i.e. 21, as well as isolation of the phosphinite congener of
8, i. e. 22, failed. NMR LIS study of the conformation in solution
of 8, and model compounds 6 and 9 revealed that 6 and 8 possess
in their most stable conformations a dihedral angle 1P of 165°,
(Figure 4.) while for 9 two stable conformations with 1P 200° and
350° are found. These results indicate that bidentate binding of
metal to heteroatom X (0, P) in the side chain, and to the tetrahedral
oxygen within lactone group is scarcely possible.

Keywords

Hrčak ID:

194326

URI

https://hrcak.srce.hr/194326

Publication date:

31.12.1981.

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