Asymmetric hydrogenation reactions mediated by a new class of bicyclic bisphosphinites

• Published in: Tetrahedron: asymmetry Vol. 10; no. 17; pp. 3341 - 3352
• Main Authors: Derrien, Nadine, Dousson, Cyril B., Roberts, Stanley M., Berens, Ulrich, Burk, Mark J., Ohff, Manuela
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 27-08-1999
• ISSN: 0957-4166; 1362-511X
• DOI: 10.1016/S0957-4166(99)00341-9

The bicyclic alcohol (−)-
4 was prepared from (−)-bicyclo[3.2.0]hept-2-en-6-one (−)-
1 in 50% yield. The diol (−)-
4 was coupled to selected chlorophosphines
6–
12 to produce a series of bisphosphinites
13–
19 in 89–95% yield. From these bisphosphinites were prepared the rhodium complexes
20–
26 which were characterised by
31P NMR and used in situ for the asymmetric hydrogenation of α-enamides
27–
29. Complexes
21,
23–
25 proved to be the superior catalysts for the production of (
R)-
N-acetylphenylalanine (91, 84, 90 and 87.5% ee) from
27 and (
S)-
N-acetylalanine methyl ester (70, 72, 68 and 71% ee) from
28.