Process and intermediates for preparing 4-substituted proline de

Details Process and intermediates for preparing 4-substituted proline de Process and intermediates for preparing 4-substituted proline de

1987-05-01

1988-03-29

Brust, Joseph Paul

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

534 15, 540602, 546208, 546213, 548518, 548537, C07D20712

Patent

active

047345080

ABSTRACT:
A process is provided for preparing 4-hydroxy-4-phenyl-proline derivatives of the structure ##STR1## wherein R.sub.1 is a nitrogen protecting group such as benzoyl, benzyloxycarbonyl, t-butoxycarbonyl, benzyl, benzhydryl, trityl, acetyl, trifluoromethylacetyl, sulfonamides, and the like and wherein X is OR.sub.2 and R.sub.2 is hydrogen or an acid protecting group such as lower alkyl, aryl-lower alkyl or a metal ion, such as Na or K, or X is NR.sub.3 R.sub.4 wherein R.sub.3 and R.sub.4 may be the same or different and are hydrogen, lower alkyl, aryl or arylalkyl, or R.sub.3 and R.sub.4 together with the nitrogen to which they are attached form a 5-, 6- or 7-membered ring. The process includes the steps of forming triphenylcerium [(C.sub.6 H.sub.5).sub.3 Ce], for example, by reacting cerium trichloride (CeCl.sub.3) with phenyllithium, and reacting the triphenylcerium with the keto acid ##STR2## in the presence of an inert organic solvent such as tetrahydrofuran. The 4-hydroxy-4-phenyl-proline derivatives used in the preparation of 4-substituted proline derivatives which are employed for preparing certain angiotensin-converting enzyme inhibitors.

REFERENCES:
patent: 4337201 (1982-06-01), Petrillo
patent: 4501901 (1985-02-01), Thottathil et al.
patent: 4588819 (1986-05-01), Thottathil
"ORganocerium Reagents. Nucleophilic Addition to Easily Enolizable Ketones", Imamoto et al., Tetrahedron Lettes, vol. 25, No. 38, pp. 4233-4236, (1984).
"Cerium Chloride-Promoted Nucleophilic Addition of Grignard Reagents to Ketones an Efficient Method for the Synthesis of Tertiary Alcohols", Tetrahedron Letters, vol. 26, No. 39, pp. 4763-4766, (1985).

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