Phosphorus compounds

Details Phosphorus compounds Phosphorus compounds

1993-09-24

1996-04-16

Tsang, Cecilia

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

548412, 549216, 568 12, 568 13, 568 17, C07D33302, C07F 928, C07F 902

Patent

active

055084389

DESCRIPTION:

BRIEF SUMMARY
The present invention is concerned with novel, racemic and optically active phosphorus compounds of the general formula ##STR3##
wherein R signifies lower alkyl, lower alkoxy, hydroxy or a protected hydroxy group, R.sup.1 and R.sup.2 are different from each other and represent lower alkyl, cycloalkyl, aryl, a five-membered heteroaromatic or a group of the formula ##STR4##
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.
The term "lower alkyl" signifies in the scope of the present invention straight-chain or branched alkyl groups with 1 to 4 carbon atoms such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl and tert.butyl. 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 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-subsituted 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. The term can, moreover, also signify naphthyl. The term "five-membered heteroaromatic" stands in the scope of the present invention for a substituent of the formula ##STR5##
Furthermore, in the substituents of formulae (a) to (d) A signifies oxygen, sulphur or --NR.sup.4. The substituent R.sup.3 signifies hydrogen, lower alkyl, especially methyl, or lower alkoxy, especially methoxy, and R.sup.4 stands for lower alkyl, preferably methyl.
Under the term "leaving group" used hereinafter there are to be understood in the scope of the present invention groups such as e.g. halogen, especially chlorine and bromine, as well as alkoxy groups such as methoxy and the like.
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 signifies methoxy or methyl. Further, there are also preferred those in which R.sup.1 and R.sup.2 represent phenyl, p-tolyl, cyclopentyl, cyclohexyl, 2- or 3-furyl or 2-thienyl. Especially preferred compounds of formula I are: osphine, (S)-P,P-dicyclohexyl-P',P'-diphenyl-(6,6'-dimethyl-biphenyl-2,2'-diyl)diph osphine, phosphine, (S)-P,P-dicyclohexyl-P',P'-di-p-tolyl-(6,6'-dimethyl-biphenyl-2,2'-diyl)di phosphine, osphine, (S)-P,P-diphenyl-P',P'-di-2-thienyl-(6,6'-dimethyl-biphenyl-2,2'-diyl)diph osphine, as well as the corresponding 6,6-dimethoxybiphenyls.
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 reacting a racemic or optically active compound of the general formula ##STR6## wherein R has the above significance, with a compound of the general formula group, reacting a thus-obtained compound of the general formula ##STR7## wherein R and R.sup.1 have the above significance, with an alkyllithium to give a compound of the formula ##STR8## wherein R and R.sup.1 have the above significance, reacting this with a compound of the general formula of a compound of formula I in which R signifies hydroxy, subjecting a corresponding compound of formula I in which R represents lower alkoxy to an ether cleavage.
The reaction of a compound of formula II with a compoun

REFERENCES:
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patent: 5021593 (1991-06-01), Nohira et al.
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Noyori et al., Chemica Scripta, 25: pp. 83-89 (1985).
Yoshikawa, et al, Tetrahedron:Asymmetry, vol. 3, No. 1 pp. 13-16 (1992).

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