| Title
| - Substituted 2-Methylene-1,3-oxazolidines, -1,3-thiazolidines,-1,3-benzothiazines, -1,3-oxazines, and SubstitutedImidazopyrimidinediones from Cl(CH2)nNCO and Cl(CH2)nNCS andActive Methylene Compounds
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| Abstract
| - The reaction of ω-chloroalkyl isocyanates Cl(CH2)nNCO (n = 2 (2), 3 (4)) and isothiocyanate Cl(CH2)2NCS (3) with active methylene compounds CH2YY‘ 1 in the presence of Et3N or Na give 2-YY‘-methylene-1,3-oxazolidines, (E,Z)-1,3-thiazolidines, and 1,3-oxazines from 2, 3, and 4, respectively. 2-(Chloromethyl)phenyl isocyanate 8 gives with 1 the corresponding benzo-oxazines. Ethyl 2-isothiocyanatobenzoate 10gives the corresponding benzothiazolinone, whereas the analogous isocyanate 12 gives noncyclic enols.Ethoxycarbonyl isothiocyanate 14 gives an open-chain thioenol or an enol-thioamide. The cyanoamidesCH2(CN)CONHR, R = H, Me, CHPh2, give with Et3N and 2 the bicyclic imidazopyrimidinediones 16,derived from two molecules of 2, but with their preformed Na salt they give the 1,3-oxazolidines. Reactionof cyanoacetamide with 3 in the presence of Na gave a tricyclic triaza(thia)indacene, derived from twomolecules of 3. A reaction mechanism involving an initial attack of the anion 1- on the NCX (X =O, S) moiety gives an anion 18, which cyclizes intramolecularly and after tautomerization gives themono-ring heterocycle. With the cyanoamides, the N- site of the ambident ion 18 attacks another moleculeof 2 giving the anion 20, which by intramolecular attack on the CN, followed by expulsion of the Cl-gives the bicyclic 16 after tautomerization.
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