KOt-Bu-promoted selective ring-opening N-alkylation of 2-oxazolines to access 2-aminoethyl acetates and N-substituted thiazolidinones

Abstract

An efficient and simple KOt-Bu-promoted selective ring-opening N-alkylation of 2-methyl-2-oxazoline or 2-(methylthio)-4,5-dihydrothiazole with benzyl halides under basic conditions is described for the first time. The method provides a convenient and practical pathway for the synthesis of versatile 2-aminoethyl acetates and N-substituted thiazolidinones with good functional group tolerance and selectivity. KOt-Bu not only plays an important role to promote this ring-opening N-alkylation, but also acts as an oxygen donor.

Layered Double Hydroxides as Reusable Catalysts for Cyclocondensation of Amidines and Aminoalcohols: Access to Multi-functionalized Oxazolines

“…17 Furthermore, the selective ring-opening Nalkylation of 3aa produced the amino-acid ester derivative 4c in medium yield (Scheme 5d). 18 Surprisingly, natural product spoxazomicin C 3baa could be directly obtained via the standard cyclocondensation of aminoalcohol 1b and amidine 2aa (Scheme 5e). 10,19 The stability and reusability of the MgAl-LDHs were examined by applying them to the model reaction between 3-amino-1,2-propanediol (1a) and benzamidine hydrochloride (2a) in five successive runs.…”

“…The ortho C–H silylation of 4a afforded the disilyl-functionalized oxazoline derivative 4b in 53% yield by using a Ru­(II) catalytic system (Scheme c) . Furthermore, the selective ring-opening N-alkylation of 3aa produced the amino-acid ester derivative 4c in medium yield (Scheme d) . Surprisingly, natural product spoxazomicin C 3baa could be directly obtained via the standard cyclocondensation of aminoalcohol 1b and amidine 2aa (Scheme e). , …”