139334-41-1Relevant academic research and scientific papers
Stereoselective synthesis of 2-oxazoline-4-carboxylates through lewis acid-catalyzed formal [3 + 2] cycloadditions of 5-alkoxyoxazoles with aldehydes: Catalytic effect of methylaluminum β-binaphthoxide on cis- selectivity
Suga,Shi,Ibata
, p. 7397 - 7405 (2007/10/02)
The formal [3 + 2] cycloadditions of 5-methoxy-2-(p-methoxyphenyl) oxazole with benzaldehyde, para- and meta-substituted benzaldehydes, propanal, cinnamaldehyde, and heterocyclic carboxaldehydes in the presence of methylaluminum β-binaphthoxide gave the corresponding methyl 5-alkyl-2-(p- methoxyphenyl)-2-oxazoline-4-carboxylates with high cis-selectivity (up to 98%). The use of ortho-substituted benzaldehydes resulted in a decrease in the cis-selectivity. The reaction of 5-methoxy-2-(p-methoxyphenyl)oxazole with benzaldehyde in the presence of titanium(IV) chloride or tin(IV) chloride gave the corresponding trans-2-oxazoline-4-carboxylate with 85-86% trans-selectivity. The reaction of ethyl glyoxylate with 5-ethoxy-2- phenyloxazole catalyzed by a 1:1 mixture of titanium(IV) chloride and titanium tetraisopropoxide gave diethyl 2-phenyl-2-oxazoline-4,5- dicarboxylate with a preference for cis-selectivity (cis/trans = 84:6). The cis-selectivity of the reaction in the presence of methylaluminum β- binaphthoxide can be explained by an antiperiplanar approach of the C4-C5 double bond of the oxazole to the aldehyde coordinated to the catalyst, followed by ring opening of the oxazole through a stepwise pathway involving zwitterionic intermediates.
Reactions of 5-alkoxyoxazoles with aldehydes in the presence of Lewis acid: Regio- and stereoselective formation of 4-alkoxycarbonyl-2-oxazolines
Suga, Hiroyuki,Shi, Xiaolan,Fujieda, Hiroki,Ibata, Toshikazu
, p. 6911 - 6914 (2007/10/02)
The [3 + 2] cycloaddition of 5-alkoxyoxazoles with aldehydes in the presence of the organoaluminum reagent, which was prepared from (±)-2,2′-dihydroxy-1,1′-dinaphthyl and AlMe3, gave cis-4-alkoxycarbonyl-2-oxazolines in high regio- and stereoselective manner.
