Substituted 2-Methylene-1,3-oxazolidines,-1,3-thiazolidines,-1,3-benzothiazines,-1,3-oxazines,and Substituted Imidazopyrimidinediones from CI(CH_2)_nNCO and C1(CH_2)_nNCS and Active Methylene Compounds

摘要

The reaction of omega-chloroalkyl isocyahates Cl(CH_2)_nNCO (n =2 (2),3 (4))and isothiocyanate C1(CH_2)_2-NCS (3)with active methylene compounds CH_2YY'1 in the presence of Et_3N 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 10 gives the corresponding benzothiazolinone,whereas the analogous isocyanate 12 gives noncyclic enols.Ethoxycarbonyl isothiocyanate 14 gives an open-chain thioenol or an enol-thioamide.The cyanoamides CH_2(CN)CONHR,R - H,Me,CHPH_2,give with Et_3N and 2 the bicyclic imidazopyrimidinediones 16,derived from two molecules of 2,but with their preformed Na salt they give the 1,3-oxazolidines.Reaction of cyanoacetamide with 3 in the presence of Na gave a tricyclic triaza(thia)indacene,derived from two molecules of 3.A reaction mechanism involving an initial attack of the anion 1~- on the N=C=X (X =O,S)moiety gives an anion 18,which cyclizes intramolecularly and after tautomerization gives the mono-ring heterocycle.With the cyanoamides,the N~ site of the ambident ion 18 attacks another molecule of 2 giving the anion 20,which by intramolecular attack on the CN,followed by expulsion of the Cl~-gives the bicyclic 16 after tautomerization.