Chiral intermediates useful for the preparation of hydroxyphosphine ligands
A compound of formula (I), wherein R 1 is hydrogen or a hydroxyl protecting group; and R 2 and R 3 are same or different and are independently selected from halogen or —O—SO 2 —X; wherein X is —C 1 -C 4 alkyl; C 1 -C 4 alkyl substituted with one or more halogen; or substituted or unsubstituted phenyl wherein said phenyl substituent is selected from halogen, nitro and C 1 -C 4 alkyl; provided that when R 3 is bromine, X is not p-toluoyl; and a process for the preparation thereof.
1. A compound of formula II:
wherein:
R 1 is hydrogen or Z;
R 2 and R 3 are same or different and are independently selected from F, Cl, Br, I;
Z is a hydroxyl protecting group selected from tetrahydro-2H-pyran-2-yl; tetrahydro-2H-pyran-2-one-3-yl; tetrahydro-2H-pyran-2-methoxy-6-yl; tetrahydro-2H-pyran-2-ethoxy-6-yl; Si(t-Bu)Me 2 ; and —C(O)Ph.
2. The compound as claimed in claim 1 , wherein R 1 is hydrogen.
3. The compound as claimed in claim 1 , wherein R 1 is tetrahydro-2H-pyran-2-yl.
4. The compound as claimed in claim 1 , wherein R 1 is Si(t-Bu)Me 2 .
5. The compound as claimed in claim 1 , wherein R 1 is —C(O)Ph.
6. The compound as claimed in claim 1 , wherein R 2 is Br.
7. The compound as claimed in claim 1 , wherein R 3 is Br.
8. A process of preparing a compound of formula II:
where:
R 1 is hydrogen or Z;
R 2 and R 3 are same or different and are independently selected from F, Cl, Br, I;
Z is a hydroxyl protecting group selected from tetrahydro-2H-pyran-2-yl; tetrahydro-2H-pyran-2-one-3-yl; tetrahydro-2H-pyran-2-methoxy-6-yl; tetrahydro-2H-pyran-2-ethoxy-6-yl;
Si(t-Bu)Me 2 ; and —C(O)Ph;
wherein said compound of formula II is obtained by protecting the hydroxyl group of the compound of formula III:
wherein said compound of formula III is obtained by hydro-halogenating a compound of formula IV:
9. The process as claimed in claim 8 , wherein said compound of formula IV is obtained by reducing a compound of formula V:
with a reducing agent to obtain a compound of formula VI:
and dehydrating the compound of formula VI in the presence of a dehydrating agent.