Production of optically pure organoboranes
AssigneeAldrich-Boranes, Inc.
InventorHerbert C. Brown
Life of this patent
Estimating the term…
Abstract
A process for upgrading to essentially 100% enantiomeric excess the optical purity of an organoborane intermediate represented by the formulae: IcpBHR* or Icp.sub.2 BR* wherein Icp is isopinocampheyl and R* is a unsubstituted or substituted, acyclic or cyclic alkyl having from 4 to 30 carbon atoms, comprising the steps of hydroborating cis-alkene, a trans-alkene or a tertiary-alkene with monoisopinocampheylborane or diisopinocampheylborane, obtaining a solid organoborane and recrystallizing the solid organoborane to obtain an enantiomeric excess of essentially 100% ee of said organoborane.
Claims32
A process for upgrading to essentially 100% enantiomeric excess the optical purity of an organoborane intermediate represented by the formulae:
- IpcBHR*
- or
- Ipc.sub.2 BR*
- wherein Ipc is isopinocampheyl, and R* is alkyl having from 4 to 30 carbon atoms comprising the steps of:
- (a) reacting an alkene selected from the group consisting of a cis-alkene, trans-alkene or tertiary-alkene with a hydroborating agent selected from the group consisting of monoisopinocampheylborane and diisopinocampheylborane;
- (b) obtaining a solid intermediate;
- and
- (c) recrystallizing the resulting solid hydroboration product from a suitable solvent to obtain a monoisopinocampheylalkylborane or diisopinocampheylalkylborane of essentially 100% enantiomeric excess.
A process for upgrading to essentially 100% enantiomeric excess the optical purity of an organoborane intermediate represented by the formula:
- IpcBHR*
- Wherein Ipc is isopinocampheyl, and R* is alkyl having from 4 to 30 carbon atoms, comprising the steps of:
- (a) reacting a trans-alkene or a tertiary-alkene with monoisopinocampheylborane;
- and
- (b) obtaining a solid intermediate;
- and
- (c) recrystallizing the resulting hydroboration product from a suitable solvent to obtain a monoisopinocampheylalkylborane of essentially 100% enantiomeric excess.
A process for upgrading to essentially 100% enantiomeric excess the optical purity of an organoborane intermediate prepared by hydroborating a cis-alkene with diisopinocampheylborane and represented by the formula
- Ipc.sub.2 BR*
- wherein Ipc is isopinocampheyl, and R* is alkyl having from 4 to 30 carbon atoms represented by the formula ##STR4## where the .alpha.-carbon is a new chiral center and where R.sub.1 and R.sub.2 are the same or different members of the group consisting of alkyl, cycloalkyl and aryl, said process comprising the steps of:
- (a) reacting a cis-alkene with diisopinocampheylborane;
- (b) obtaining a solid organoborane;
- and
- (c) recrystallizing said solid organoborane from a suitable solvent.
A process for upgrading to essentially 100% enantiomeric excess the optical purity of an organoborane intermediate prepared by hydroborating a cis-alkene with diisopinocampheylborane and represented by the formula
- Ipc.sub.2 BR*
- wherein Ipc is isopinocampheyl, and R* is an alkyl group having from 4 to 30 carbon atoms represented by the formula ##STR5## where the .alpha.-carbon is a new chiral center and where R.sub.1 and R.sub.2 are the same or different members of the group consisting of alkyl, cycloalkyl and aryl, said process comprising the steps of:
- (a) reacting a cis-alkene with diisopinocampheylborane to obtain a non-solid borane hydroboration product;
- (b) converting said non-solid borane to a solid compound selected from the group consisting of a borate, a borane complex and a chelate by treatment with a compound selected from the group consisting of a strong base, an amine having low steric requirements and an aminoethanol chelating agent;
- and
- (c) recrystallizing said solid from a suitable solvent to obtain a diisopinocampheylalkylborane of essentially 100% enatiomeric excess.
A process for upgrading to essentially 100% enantiomeric excess the optical purity of organoborane intermediates prepared by hydroborating a trans-alkene or tertiary-alkene with monoisopinocampheylborane and represented by the formula:
- IpcBHR*
- wherein Ipc is isopinocampheyl and R* is alkyl, cycloalkyl or aryl, said process comprising the steps of:
- (a) reacting a trans-alkene or tertiary-alkene with monoisopinocampheylborane to obtain a non-solid borane hydroboration product;
- (b) converting said non-solid borane so obtained to a solid selected from the group consisting of a borate, a boron complex and a chelate by treatment with a compound selected from the group consisting of a strong base, an amine having low steric requirements and an aminoethyl chelating agent;
- and
- (c) recrystallizing said solid from a suitable solvent to obtain a monoisopinocampheylalkylborane of essentially 100% enantiomeric excess.
Dependencies are inferred from the claim text.