Biphenyldiphosphine compounds
AssigneeThe Hong Kong Polytechnic University
InventorsAlbert Sun-Chi Chan, Liqin Qiu
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Abstract
The present invention provides compounds of the formula wherein R is optionally substituted lower alkyl, cycloalkyl or aryl; R′ is alkyl or aryl; n is zero or an integer of 1 or 2; or an enantiomer thereof; or an enantiomeric mixture thereof. The compounds of formula (I) are bridged C2-symmetric biphenyldiphosphine analogs and, thus, may be employed as ligands to generate chiral transition metal catalysts which may be applied in a variety of asymmetric reactions. The compounds of the present invention are easily accessible in high diastereomeric and optical purity according to the methods disclosed herein.
Claims35
A compound of the formula
- wherein
- R is optionally substituted lower alkyl, cycloalkyl or aryl;
- R′ is alkyl or aryl;
- n is zero or an integer of 1 or 2;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof.
A catalyst comprising a transition metal bound to a compound of the formula
- wherein
- R is optionally substituted lower alkyl, cycloalkyl or aryl;
- R′ is alkyl or aryl;
- n is zero or an integer of 1 or 2;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof.
A method for preparing a compound of the formula
- wherein R is optionally substituted lower alkyl, cycloalkyl or aryl;
- R′ is alkyl or aryl;
- and n is zero or an integer of 1 or 2;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- which method comprises:
- (a) reacting a phenol of the formula
- wherein X is chloro, bromo or iodo;
- with an alkylating agent of the formula
- wherein Lg represents a leaving group;
- and R and n have meanings as defined for formula (I);
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- in the presence of a base and an inert organic solvent to afford a compound of the formula
- wherein R, n and X have meanings as defined above;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- (b) dehalogenating a compound of formula (IV) in an inert organic solvent, and treating the resulting dianion with a phosphine chloride of the formula
- R′2PCl (V)
- wherein R′ is alkyl or aryl;
- to afford a compound of the formula
- wherein R, n and R′ have meanings as defined above;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- (c) treating a compound of formula (VI) with an oxidizing agent to afford a compound of the formula
- wherein R, n and R′ have meanings as defined above;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- (d) deprotonating a compound of formula (VII) in an inert organic solvent, and treating the resulting dianion with an iodine source to afford a compound of the formula
- wherein R, n and R′ have meanings as defined above;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- (e) treating a compound of formula (VIII) with copper in an inert organic solvent to afford a compound of the formula
- wherein R, n and R′ have meanings as defined above;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- and
- (f) treating a compound of formula (IX) with a reducing agent in an inert organic solvent to afford a compound of formula (I) wherein R, n and R′ have meanings as defined above;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof.
A method for preparing a compound of the formula
- wherein R is optionally substituted lower alkyl, cycloalkyl or aryl;
- R′ is alkyl or aryl;
- and n is zero or an integer of 1 or 2;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- which method comprises:
- (a) treating a compound of the formula
- wherein R, n and R′ have meanings as defined for formula (I);
- with copper in an inert organic solvent to afford a compound of the formula
- wherein R, n and R′ have meanings as defined above;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- and
- (b) treating a compound of formula (IX) with a reducing agent in an inert organic solvent to afford a compound of formula (I) wherein R, n and R′ have meanings as defined above;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof.
A method for preparing a compound of the formula
- wherein R is optionally substituted lower alkyl, cycloalkyl or aryl;
- R′ is alkyl or aryl;
- and n is zero or an integer of 1 or 2;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- which method comprises:
- (a) reacting a compound of the formula
- wherein R′ has a meaning as defined for formula (I);
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- with an alkylating agent of the formula
- wherein Lg represents a leaving group;
- and R and n have meanings as defined for formula (I);
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- in the presence of a base and an inert organic solvent to afford a compound of the formula
- wherein R, n and R′ have meanings as defined above;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof;
- and
- (b) treating a compound of formula (IX) with a reducing agent in an inert organic solvent to afford a compound of formula (I) wherein R, n and R′ have meanings as defined above;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof.
A method for converting a prochiral substrate to a chiral product by an asymmetric reaction in the presence of a catalyst comprising a transition metal bound to a compound of the formula
- wherein
- R is optionally substituted lower alkyl, cycloalkyl or aryl;
- R′ is alkyl or aryl;
- n is zero or an integer of 1 or 2;
- or an enantiomer thereof;
- or an enantiomeric mixture thereof.
Dependencies are inferred from the claim text.