Fortuitous Enantiomeric Self-Rectification of an Unreported Partial Racemisation in the Synthesis of a Chiral Phosphoric Acid: A Warning to Practitioners
DOI: 10.14469/hpc/14345 Metadata
Created: 2024-06-18 12:49
Last modified: 2024-10-03 16:24
License: Creative Commons: Public Domain Dedication 1.0
Funding: (none given)
Co-author: Ben Lancaster Co-author: D. Christopher Braddock
Description
MOM deprotection during a routine synthesis of phosphoric acid 1 promoted partial racemisation of the product BINOL 5. Surprisingly, however, after phosphorylation of the partially racemised BINOL, enantiopure acid 1 was isolated. Further inspection revealed that during phosphorylation, unhydrolysed racemic phosphorochloridate 6 precipitated, thus restoring homochirality in the product phosphoric acid 1. Moreover, MOM deprotection partial racemisation was avoided by conducting reactions at lower temperatures for no longer than the required deprotection time, and/or by application of other deprotection conditions from the literature.
Members
| DOI | Description |
|---|---|
| 10.14469/hpc/14353 | rac-3,3'-Di(phenanthren-9-yl)-[1,1'-binaphthalene]-2,2'-diyl phosphorochloridate (rac-6) |
| 10.14469/hpc/14347 | (R)-(+)-2,2'-Bis(methoxymethoxy)-1,1'-binaphthalene (2) |
| 10.14469/hpc/14348 | (R)-(−)-3,3'-Diiodo-2,2'-bis(methoxymethoxy)-1,1'-binaphthalene (3) |
| 10.14469/hpc/14350 | (R)-(+)-9,9'-(2,2'-Bis(methoxymethoxy)-[1,1'-binaphthalene]-3,3'-diyl)diphenanthrene (4) |
| 10.14469/hpc/14351 | (R)-(+)-3,3'-Di(phenanthren-9-yl)-[1,1'-binaphthalene]-2,2'-diol (5) |
| 10.14469/hpc/14354 | (R)-(−)-3,3'-Di(phenanthren-9-yl)-[1,1'-binaphthalene]-2,2'-diyl hydrogen phosphate (1) |