Phosphorus compounds

Details Phosphorus compounds Phosphorus compounds

1993-09-27

1995-10-10

Shaver, Paul F.

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

Organic compounds

Silicon containing

568 17, C07F 708, C07F 950

Patent

active

054572193

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/CH 93/00026 Feb. 1, 1993.
The present invention is concerned with novel, racemic and optically active phosphorus compounds of the general formula ##STR2## wherein R signifies lower alkyl or lower alkoxy and R.sup.1 represents lower alkyl, cycloalkyl or substituted phenyl.
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, enantiosetective 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 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. The term "cycloalkyl" signifies three- to five-membered rings such as cyclopropyl, cyclobutyl and cyclopentyl, especially cyclobutyl and cyclopentyl. The term "substituted phenyl" signifies in the scope of the present invention the phenyl residue which can be substituted in the meta- or para-position or which can also be meta, meta-substituted. As substituents there come into consideration phenyl, trialkylsilyl and diphenylalkylsilyl such as trimethylsilyl, triethylsilyl, diphenyl-tert.butylsilyl 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 signifies methoxy or methyl, especially methoxy. Further, there are also preferred those in which R.sup.1 signifies isopropyl, isopentyl, cyclopentyl or substituted phenyl. In this case, the phenyl ring is preferably substituted in the para- or meta, meta-position, namely with phenyl, trimethylsilyl or also triethylsilyl. Especially preferred compounds of formula I are: (S)-(6,6'-Dimethoxybiphenyl-2,2'-diyl)bis(di-4-biphenylylphosphine). (S)-(6,6'-Dimethoxybiphenyl-2,2'-diyl)bis[bis-[4-(trimethylsilyl)phenyl]ph osphine]. (S)-(6,6'-Dimethoxybiphenyl-2,2'-diyl)bis[di-(meta-terphenyl-5'-yl)phosphi ne]. (S)-(6,6'-Dimethoxybiphenyl-2,2'-diyl)bis[bis(3,5-bis(trimethylsilyl)pheny l)phosphine]. (S)-(6,6'-Dimethoxybiphenyl-2,2'-diyl)bis[bis(3,5-bis(triethylsilyl)phenyl )phosphine].
The compounds of formula 1 in accordance with the invention can be manufactured in a manner known per se. This can be carried out e.g. starting from compounds of general formula II ##STR3## wherein R has the above significance and R.sup.2 represents phenoxy, chlorine or bromine.
The manufacture is carried out e.g. by reacting a compound of formula II with a Grignard or lithium compound of the formula formula III ##STR4## wherein R and R.sup.1 have the above significance, which is subsequently reduced to a compound of formula I.
The reaction of a compound of formula II with R.sup.1 MgX or R.sup.1 Li can be carried out in a manner known per se. This is preferably carried out e.g. under the usual conditions of a Grignard reaction. In this case, compounds of formula II in which R.sup.2 represents phenoxy are preferably reacted with a compound of the formula R.sup.1 MgX and those in which R.sup.2 represents chlorine are preferably reacted with a compound of the formula R.sup.1 --Li or R.sup.1 MgX.
The reduction of a compound of formula III, which is racemic or present in the (R)- or (S)-form, can be carried out in a manner known per se. This can be carried out, for example, with silanes such as e.g. trichlorosilane, in an aromatic hydrocarbon, such as, for example, in boiling xylene, or also in acetonitrile etc., conveniently in the presence of an adjuvant base, such as, for example, triethylamine or preferably tributylamine. If desired, this reduction can also be carried out in an autoclave under pressure.
The compounds of formula II which are used as starting materials are known compounds and can be prepared e.g. according to WO

REFERENCES:
patent: 4556740 (1985-12-01), Hansen et al.
patent: 4956055 (1990-09-01), Puckette
patent: 5021593 (1991-06-01), Nohira et al.
Derwent Abstract B05 E11 J04 E19 (1990) for EP 398 132.

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