The first enantioselective direct aldol addition of N-Boc-oxindoles to polymeric ethyl glyoxylate is presented. The reaction is performed by using as low as 0.1 mol% (DHQ)2PHAL and gives access to a-hydroxycarboxylate derivatives bearing adjacent secondary alcohol and quaternary stereocenters with high levels of diastereo- and enantiocontrol. The use of ethyl glyoxylate in its polymeric form represents an important advantage for synthetic applications and allows us to directly install a C2 unit ready to be converted in useful building blocks. A further one-pot protection/deprotection sequence catalyzed by ZnACHTUNGTRENUNG(ClO4)2·6H2O preserved the a-hydroxycarboxylates from racemization by means of a parasitic alcohol-catalyzed retroaldol reaction.

Cinchona Alkaloid-Catalyzed Enantioselective Direct Aldol Reaction of N-Boc-Oxindoles with Polymeric Ethyl Glyoxylate

PESCIAIOLI, FABIO;RIGHI, PAOLO;MAZZANTI, ANDREA;MANCINELLI, MICHELE;BARTOLI, GIUSEPPE;BENCIVENNI, GIORGIO
2011

Abstract

The first enantioselective direct aldol addition of N-Boc-oxindoles to polymeric ethyl glyoxylate is presented. The reaction is performed by using as low as 0.1 mol% (DHQ)2PHAL and gives access to a-hydroxycarboxylate derivatives bearing adjacent secondary alcohol and quaternary stereocenters with high levels of diastereo- and enantiocontrol. The use of ethyl glyoxylate in its polymeric form represents an important advantage for synthetic applications and allows us to directly install a C2 unit ready to be converted in useful building blocks. A further one-pot protection/deprotection sequence catalyzed by ZnACHTUNGTRENUNG(ClO4)2·6H2O preserved the a-hydroxycarboxylates from racemization by means of a parasitic alcohol-catalyzed retroaldol reaction.
F. Pesciaioli; P. Righi; A. Mazzanti; C. Gianelli; M. Mancinelli; G. Bartoli; G. Bencivenni
File in questo prodotto:
Eventuali allegati, non sono esposti

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/112799
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 14
  • ???jsp.display-item.citation.isi??? 11
social impact