1-Allyl-2-pyrroleimines obtained from (S)-valinol and (S)-phenylglycinol underwent highly diastereoselective addition of allylmagnesium chloride, used in excess amounts, to give the corresponding secondary amines with concomitant allyl to (Z)-1-propenyl isomerisation of the 1-pyrrole substituent. Transformation of the 2-aminoalcohol moiety to an oxazolidinone, or its cleavage and subsequent N-protection, followed by ring closing metathesis of the two alkene groups gave the unsaturated bicyclic compound. Full hydrogenation of the alkene function and the aromatic rings afforded the indolizidine derivative as a mixture of two or three diastereomers with a ratio which was dependent on the nature of both the N-substituent and the catalyst. The two prevalent diastereomers were isolated and their configuration was determined by X-ray crystallographic analysis.
Asymmetric synthesis of 8-aminoindolizidine from chiral 2-pyrroleimines / V. G. Albano; A. Gualandi; M. Monari; D. Savoia. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - STAMPA. - 73:(2008), pp. 8376-8381. [10.1021/jo8014598]
Asymmetric synthesis of 8-aminoindolizidine from chiral 2-pyrroleimines
ALBANO, VINCENZO GIULIO;GUALANDI, ANDREA;MONARI, MAGDA;SAVOIA, DIEGO
2008
Abstract
1-Allyl-2-pyrroleimines obtained from (S)-valinol and (S)-phenylglycinol underwent highly diastereoselective addition of allylmagnesium chloride, used in excess amounts, to give the corresponding secondary amines with concomitant allyl to (Z)-1-propenyl isomerisation of the 1-pyrrole substituent. Transformation of the 2-aminoalcohol moiety to an oxazolidinone, or its cleavage and subsequent N-protection, followed by ring closing metathesis of the two alkene groups gave the unsaturated bicyclic compound. Full hydrogenation of the alkene function and the aromatic rings afforded the indolizidine derivative as a mixture of two or three diastereomers with a ratio which was dependent on the nature of both the N-substituent and the catalyst. The two prevalent diastereomers were isolated and their configuration was determined by X-ray crystallographic analysis.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.