Phosphorus compounds

Details Phosphorus compounds Phosphorus compounds

1993-09-27

1995-07-04

Richter, Johann

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

Organic compounds

Phosphorus containing

568 13, C07F 950

Patent

active

054301912

DESCRIPTION:

BRIEF SUMMARY
This application is the National Stage Application of PCT/CH93/00025 filed Feb. 1, 1993.
The present invention is concerned with novel, racemic and optically active phosphorus compounds of the general formula ##STR2## wherein R signifies hydroxy or a protected hydroxy group, R.sup.1 represents hydroxy, a protected hydroxy group or lower alkoxy and R.sup.2 represents lower alkyl, cycloalkyl, aryl or together with the phosphorus atom a group of the formula
The invention is also concerned with the manufacture of the phosphorus compounds of formula I and with their use for enantioselective reactions such as e.g. asymmetric hydrogenations, enantioselective hydrogen displacements in prochiral, allylic systems, and the like. Moreover, the compounds of formula 1 in which R and R.sup.1 both represent hydroxy groups can be used as starting materials for the manufacture of other diphosphines, e.g. of compounds of formula I in which R and/or R.sup.1 represent(s) a protected hydroxy group.
The term "lower alkyl" signifies in the scope of the present invention straight-chain or branched alkyl groups with 1 to 5 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert.butyl, pentyl, isopentyl and the like. The term "lower alkoxy" signifies groups in which the alkyl residue has the foregoing significance. As protecting groups for the hydroxy group there especially come into consideration in the scope of the present invention the usual ether-forming groups such as e.g. benzyl, allyl, benzyloxymethyl, lower alkoxymethyl or also 2-methoxyethoxymethyl and the like. The term "cycloalkyl" signifies here three- to seven-membered rings such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl, especially cyclopentyl and cyclohexyl. The term "aryl" signifies in the scope of the present invention especially the phenyl residue which can be not only unsubstituted but also multiply-substituted in the ortho-, meta- or para-position. Substituents which come into consideration in this case are phenyl, lower alkyl or lower alkoxy groups, preferably methyl or methoxy groups, or also di-lower alkyl-amino, preferably dimethylamino, groups, as well as fluorine or also trialkylsilyl such as trimethylsilyl and the like. Moreover, the term can also signify naphthyl.
The phosphorus compounds of formula I can be present not only in racemic form but also in optically active form. Preferred compounds of formula I are those in which R represents hydroxy and R.sup.1 represents a protected hydroxy group or an alkoxy group, especially a benzyloxy group or an isopropyloxy group, and also those in which R and R.sup.1 are the same, especially those in which R and R.sup.1 both represent a hydroxy group or a benzyloxy group. Compounds in which R.sup.2 represents phenyl, isopropyl, cyclopentyl or cyclohexyl are also preferred. Especially preferred compounds of formula I are:
(R)- or (S)-(6,6'-Dihydroxybiphenyl-2,2'-diyl)bis(diphenylphosphine),
(R)- or (S)-(6,6'-dibenzyloxybiphenyl-2,2'-diyl)bis(diphenylphosphine ),
(R)- or (S)-(6-hydroxy-6'-isopropoxybiphenyl-2,2'-diyl)bis(diphenylphosphine).
The compounds of formula I in accordance with the invention can be manufactured in a manner known per se. This can be carried out e.g. by subjecting a racemic or optically active compound of the general formula ##STR3## wherein R.sup.2 has the above significance, to an ether cleavage. There are thus obtained compounds of formula I in which R and R.sup.1 signify hydroxy. Such compounds can, in turn, be readily converted in a manner known per se into compounds of formula I in which R and/or R.sup.1 represent(s) a protected hydroxy group or into such compounds in which R signifies hydroxy and R.sup.1 represents lower alkoxy.
The ether cleavage of a compound of formula I in which R represents lower alkoxy can be carried out in a manner known per se, e.g. by means of boron tribromide and the like. This is conveniently carried out in an inert organic solvent, e.g. in a halogenated hydrocarbon such as, for example, methylene chloride and the l

REFERENCES:
patent: 4556740 (1985-12-01), Hansen et al.
patent: 5021593 (1991-06-01), Nohira et al.
Derwent Abstract B05 E11 J04 E19 (1990) for EP 398 132.
Greene et al., in "Protective Groups in Organic Synthesis, 2nd ed.", 1991, John Wiley & Sons, Inc., pp. 10-16.

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