Chiral diols, their manufacture and ligands and catalysts derived therefrom
AssigneeCiba Specialty Chemical Corporation
InventorUlrich Berens
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Abstract
The present invention relates to a method for the preparation of C2-symmetric 1,4-diols of the formula IVA or IVB, wherein ring A, R1 and R2 have the meanings given in the specification, that makes use of the metallation of pure enantiomers of α-(aryl or heteroaryl)-α-substituted alkanol compounds or the use of said alkanol compounds in the preparation of said mmetric 1,4-diols; novel C2-symmetric 1,4-diols in enantiomerically pure form; and methods of use or their use in the synthesis of chiral ligands which find use to produce catalysts for a variety of asymmetric transformations such as hydrogenations.
Claims13
A process for the preparation of C2-symmetric 1,4-diols of the formula IVA or IVB having a high enantiomeric purity
- wherein ring A which includes the shown double bond forms a mono-, di- or polycyclic aromatic or heteroaromatic ring and R1 and R2 are, independently of each other, an organic moiety,
- the process comprising reacting an α-(aryl or heteroaryl)-α-substituted alkanol compound of the formula IA (for the synthesis of a compound of the formula IVA) or IB (for the synthesis of a compound of the formula IVB)
- wherein ring A and R1 are as defined under formula IVA and IVB, with a lithiating reagent, obtaining an intermediate of the formula IIA (from IA) or IIB (from IB),
- wherein ring A and R1 have the meanings given under compounds of the formulae IVA and IVB, said process further comprising reacting the lithiated product of the formula IIA or IIB, respectively, with an N,N-di-alkyl-formamide to form a hemiacetal compound of the formula IIIA (from IIA) or IIIB (from IIB),
- wherein ring A, R1 and R2 have the meanings indicated for compounds of the formula IVA and IVB, and subsequently with a Grignard reagent of the formula R2MgX wherein R2 is an organic moiety and X is halogen or, alternatively, using corresponding lithium, zinc or other metal comprising compounds that allow for introduction of R2;
- to yield the corresponding compounds of formula IVA (from IIIA) and IVB (from IIIB).
The process according to claim 6, further comprising reacting the compound of the formula
- wherein ring A, R1 and R2 have the meanings indicated for compounds of the formula IVA and IVB in claim 9 and Ar is aryl, with a phosphine of the formula IX or IX*,
- R3—PH2 (IX)
- H2P—R3*—PH2 (IX*)
- (or the corresponding borane adduct thereof) wherein R3 is a monovalent and R3* a bivalent organic moiety that can be bound to phosphorus, resulting in a phospholane compound of the formula XA or XA* (from VIIIA);
- or XB or XB* (from VIIIB) shown in claim 6, respectively.
Dependencies are inferred from the claim text.