Abstract1-Alkylamino-3-(2-vinyloxyethoxy)-2-propanols react with 3-and 4-pyridinecarbaldehydes to give equimolar mixtures of cis-and trans-3-alkyl-5-(2-vinyloxyethoxymethyl)-2-[3(4)-pyridyl]oxazolidines.2 2 1+5 2+ 2 2 5&+2 2 15 5Pyridine derivatives exhibit versatile biological activity [1]. A wide spectrum of biological activity is also inherent to such amino alcohol derivatives as vinyl ethers [2] and cyclic N,O-acetals (oxazolidines) [3]. Undoubtedly, substances whose molecules include fragments of the above compounds (vinyloxy group and oxazolidine and pyridine rings) attract interest from the viewpoint of their biological activity.In the present work we synthesized 3-alkyl-2-[3(4)-pyridyl]-5-(2-vinyloxyethoxymethyl)oxazolidines IaIj in 2788% yield by condensation of 1-alkylamino-3-(2-vinyloxyethoxy)-2-propanols IIaIIe with 3-and 4-pyridinecarbaldehydes IIIa and IIIb (Scheme 1). The reactions were carried out by heating equimolar mixtures of the reactants in boiling benzene with simultaneous removal of water as azeotrope. We failed to effect condensation of 1-tert-butylamino-3-(2-vinyloxyethoxy)-2-propanol with aldehydes IIIa and IIIb even in the presence of acid catalysts such as p-toluenesulfonic acid and orthophosphoric acid and using toluene as solvent with a higher boiling point. Presumably, the reason is steric hindrances created by the bulky tert-butyl group.Oxazolidines IaIj were formed as equimolar mixtures of trans and cis isomers. This followed from the presence in the 1 H NMR spectra of Ia, Ic, and IeIi of two singlets with equal intensities in the region d 4.685.07 ppm; these signals belong to proton in position 2 of the oxazolidine ring. The difference in the chemical shifts of isomeric oxazolidines was 0.01 to 0.04 ppm. The corresponding difference for compounds Ib, Id, and Ij was small, so that the OCHN signals from their trans and cis isomers merged together, and only one slightly broadened singlet was observed in the 1 H NMR spectra. Nevertheless, the presence of two isomers followed from increased multiplicity of the NCH 2 signals, which was typical of all compounds except for Ia (R = Me). Presumably, the substituent on the nitrogen atom in isomeric oxazolidines occupies different positions with respect to the nearby magnetically anisotropic pyridine ring. On the other hand, more distant protons in the vinyloxy group of the substituent in position 5 of the oxazolidine do not suffer from the above effect, and their signals are not doubled.The reactions of aldehydes IIIa and IIIb with amino alcohol IIf could give rise to mixtures of isomeric products I, R = Me, R' = 3-Py (a); R = Bu, R' = 3-Py (b); R = EtO(CH 2 ) 2 , R' = 3-Py (c); R = CH 2 =CHO(CH 2 ) 2 , R' = 3-Py (d); R = CH 2 =CHO(CH 2 ) 3 , R' = 3-Py (e); R = Me, R' = 4-Py (f); R = Bu, R' = 4-Py (g); R = EtO(CH 2 ) 2 , R' = 4-Py (h); R = CH 2 =CHO(CH 2 ) 2 , R' = 4-Py (i); R = CH 2 =CHO(CH 2 ) 3 , R' = 4-Py (j); II, R = Me (a), Bu (b), EtO(CH 2 ) 2 (c), CH 2 =CHO(CH 2 ) 2 (d), CH 2 =CHOCH 2 ) 3 (e); III, R' = 3-Py (a), 4-Py (b).
