ChemInform Abstract: SYNTHESIS, STRUCTURE, AND PROPERTIES OF 1,3‐OXAZACYCLOALKANES (REVIEW)

Five-membered oxaza heterocyclic compounds on the basis of epoxides and aziridines

“…Acid hydrolysis of 1,3-oxazolidines gave N-sulfonyl amino alcohols with high enantioselectivity. The possibility for synthesizing oxazolidines by reactions of aziridines with aldehydes and ketones was noted in review [218]. N-Tosylaziridines were proposed as building blocks for the synthesis of oxazolidines; these reagents readily react with various dipolarophiles according to the [3 + 2]-cycloaddition pattern to produce five-membered nitrogen-containing heterocycles 216 (Ar = 4-ClC 6 H 4 , 4-MeC 6 H 4 ; R 1 = R 2 = H, Me, Et, Pr) [240] (Scheme 124).…”

“…Oxazolidines 182 having cagelike fragments were synthesized [216,217]. Apart from vicinal amino alcohols, oxazolidines can be obtained from their precursors, such as epoxides, aziridines, and unsaturated compounds [8,218]. Since 1960s, oxazolidines were prepared by reaction of oxiranes with Schiff bases (Scheme 106); in first 828 experiments, the yield of heterocycles was as low as 8-10%, and Lewis acids (BF 3 · Et 2 O, SnCl 4 ) were proposed to improve the yield [218][219][220][221].…”

“…Apart from vicinal amino alcohols, oxazolidines can be obtained from their precursors, such as epoxides, aziridines, and unsaturated compounds [8,218]. Since 1960s, oxazolidines were prepared by reaction of oxiranes with Schiff bases (Scheme 106); in first 828 experiments, the yield of heterocycles was as low as 8-10%, and Lewis acids (BF 3 · Et 2 O, SnCl 4 ) were proposed to improve the yield [218][219][220][221]. In the synthesis of oxazolidine 183 (R = Alk), dicyclopentadienylzirconium dichloride turned out to be more effective than tin(IV) chloride; no catalyst was necessary to obtain N-aryl derivatives 183 (R = Ar) [17].…”

Condensation of N-(2-hydroxybenzylidene)-1,2-aminoalkanols with formaldehyde

“…1 Recently we reported that the condensation of N-(2-hydroxybenzylidene)-2-aminoethanol with formaldehyde resulted in 2,3-dihydro-10b-H- [1,3]oxazolo-[3,2-с]- [1,3]benzoxazine. 2 The compounds of this class are promising as biologically active agents, owing to the presence of both penta-and hexa-O,N-acetal rings in their structures.…”

“…The present work deals with the effect of different substituents positioned in the amino-alcohol fragment and the benzene ring of N-(2-hydroxybenzylidene)-2-aminoethanol on the polycondensation reaction with aldehydes as well as on the structures and yields of the products obtained. New 2,3-dihydro-10b-H- [1,3] …”