143539-92-8Relevant articles and documents
Stereoselective Homologation-Amination of Aldehydes by Addition of Their Nitrones to C-2 Metalated Thiazoles - A General Entry to α-Amino Aldehydes and Amino Sugars
Dondoni, Alessandro,Franco, Santiago,Junquera, Federico,Merchan, Francisco L.,Merino, Pedro,et al.
, p. 505 - 520 (2007/10/03)
A general method for the homologation of aldehydes to α-amino aldehydes (aminohomologation) has been developed, which employs nitrones as iminium derivatives of the aldehydes.Key operations include a) the addition of a thiazole metalated at C-2 to the N-benzylnitrone derived from the aldehyde, b) the reductive dehydroxylation of the resultant thiazolyl N-benzylhydroxylamine, and c) the unmasking of the formyl group from the thiazole ring.The homologation sequence was studied by employing nitrones derived from various chiral polyalkoxy aldehydes and dialdoses.The addition of 2-lithiothiazole to these nitrones was syn-selective, whereas the reaction with the same nitrones precomplexed with Lewis acids was anti-selective.Hence, from each nitrone a pair of diastereoisomeric hydroxylamines was obtained.These compounds were then converted by the above sequence into α-epimeric α-amino aldehydes.Model elaborations of some of these products afforded the amino sugars D-glucosamine, D-mannosamine, D-nojirimycin, and advanced intermediates for the synthesis of destomic acid and lincosamine. - Keywords: amino aldehydes; aminohomologation; amino sugars; nitrones; thiazoles
