“…The γ- N -hydroxyamino esters 9 are also ready precursors of γ-lactams, which are found in numerous biologically active molecules . Hydrogenation of 9c and 9e in acetic acid, followed by removal of the palladium catalyst and heating, effected reduction of the N−O bond, cyclization, and cleavage of the benzylic group to yield directly lactams 16c and 16e , respectively (Scheme ). 5 Conversion of γ- N -hydroxyamino Esters 9c and 9e into Lactams 16c and 16e …”
The title compound has proven to be an excellent chiral auxiliary for nitrones in SmI2-mediated reductive coupling with alpha,beta-unsaturated esters. A variety of such nitrones, prepared from aldehydes and enantiopure N-hydroxy-1-(2,4,6-triisopropylphenyl)ethylamine, afforded gamma-N-hydroxyamino esters in high yields and diastereomeric purity. These adducts, readily available as either enantiomer, could be transformed into gamma-N-acetoxyamino esters, N-Boc-gamma-amino esters, and gamma-lactams.
“…The γ- N -hydroxyamino esters 9 are also ready precursors of γ-lactams, which are found in numerous biologically active molecules . Hydrogenation of 9c and 9e in acetic acid, followed by removal of the palladium catalyst and heating, effected reduction of the N−O bond, cyclization, and cleavage of the benzylic group to yield directly lactams 16c and 16e , respectively (Scheme ). 5 Conversion of γ- N -hydroxyamino Esters 9c and 9e into Lactams 16c and 16e …”
The title compound has proven to be an excellent chiral auxiliary for nitrones in SmI2-mediated reductive coupling with alpha,beta-unsaturated esters. A variety of such nitrones, prepared from aldehydes and enantiopure N-hydroxy-1-(2,4,6-triisopropylphenyl)ethylamine, afforded gamma-N-hydroxyamino esters in high yields and diastereomeric purity. These adducts, readily available as either enantiomer, could be transformed into gamma-N-acetoxyamino esters, N-Boc-gamma-amino esters, and gamma-lactams.
AlkaloidsAlkaloids U 0600 Radical Carboazidation: Expedient Assembly of the Core Structure of Various Alkaloid Families. -A one-pot radical addition-azidation of terminal alkenes is developed which affords the corresponding azides [cf. (III)] in moderate to good yields. This method is successfully coupled with an azide reduction to give aminoesters which spontaneously cyclize towards pyrrolidinone derivatives [cf. (IV)]. Pyrrolizidinones (VIII) as well as spirocyclic pyrrolidinones (XI) are also achieved using this technique, and the application to the synthesis of compound (XIV), an advanced intermediate in alkaloid synthesis, is also demonstrated. -(PANCHAUD, P.; OLLIVIER, C.; RENAUD*, P.; ZIGMANTAS, S.; J. Org. Chem. 69 (2004) 8, 2755-2759; Inst. Chem. Biochem., Univ. Bern, CH-3012 Bern, Switz.; Eng.) -Mischke 33-215 2004 Alkaloids
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