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The addition of HBr to tertiary cyanoacetylenic alcohols is accompanied by intramolecular cyclization, which leads to the hydrobromides of bromiminodihydrofurans.

2-Iminobenzimidazo-1,3-thiazines containing a hydroxyl group were obtained by the reaction of benzimid-azole-2-thione with tertiary cyanoacetylene alcohols. It was observed that they have enhanced stability toward alkalis.

New ω-arylenyne ethers and thioethers were prepared by the acetylenic condensation of 1-alkoxy-(1-ethylthio)-1-buten-3-ynes with a series of substituted iodobenzenes in the presence of CuI.

It was shown that nitrogen-containing ethynyl vinyl ethers can be synthesized from tertiary diacetylenic alcohols and amino alcohols in the presence of alkaline catalysts.

The reaction of 2-methyl-3,5-heptadiyn-2-ol withα-glycols in the presence of alkaline catalysts results in the formation of 1,3-dioxolanes, whileβ-glycols give ethynylvinyl ethers which contain a hydroxyl group in the alkoxy residue.

During the reaction of l-cyano-3-methyl-3-hydroxy-l-pentyne (I) with Na2S'9H20 in the presence of potassium hydroxide (in the ratio of 0.4:1:1; 20~ dioxane), 2-methyl-2-ethyl3,4-di(cyanomethylene)oxetane (III), a product of the autoheterocyclization of carbinol I, was obtained instead Of the expected sulfide according to [i]. It is possible that cyanoethylene, formed as the result of the inverse Favorski reaction, is added in the form of an anion to the triple bond of the initial carbinol, which is very electrophilic in character. Then, the intermediate carbinol II cyclizes into III in a yield of 55%, mp 89~ (from ether). IR spectrum (KBr): 1650 (C----CH), 2220 cm -~ (CN); PMR spectrum (i00 MHz, CDCI3): 1.65 (s, 2-CH~); 1.20 (t, 2-CH2-CH3) and 1.88 (qu, 2-CH2); 5.55 (s, 3'-CH); 5.13 ppm (s, 4'-CH), f3',4' = 0.6 Hz.

The spectra are discussed and many assignments made from considerations of the bond anisotropies. Double resonance provided some checks and gave |Jgem| for the α-methylene protons of hexahydropyrrolizine.Over the range –70 to +190° hexahydropyrrolizine exists mainly, if not entirely, in the cis-fused form. The 3-endo-methyl derivative, however, shows rapid nitrogen inversion at room temperature, and only below –60° does it exist predominantly in the cis-fused form. Incidentally, the configurations of the two stereoisomers of 3-methylhexahydropyrrolizine were confirmed.The shielding of the methyl group in hexahydropyrrolizine methiodide is compared with that in the methiodides of cis-and trans-octahydroindolizine and of trans-octahydroquinolizine.

In order to study the reaction mechanism of the catalytic intramolecular conversion of heterocycles [1–3] and to broaden the field of their application, we have studied the dehydration over Al2O3 of 1-amino-3-(α-tetrahydrofuryl) propane (I), 1-methylamino-1-(α-tetrahydrofuryl) propane (II), and 2-(3-hydroxy-1-propyl)-1-methylpyrrolidine (III), leading in all three cases to pyrrolizidine (IV).