Chinazolincarbonsäuren. XII. Mitteilung . Synthese von [2‐(Ethoxycarbonyl)‐3,4‐dihydro‐4‐oxochinazolin‐3‐yl]‐, [2‐(Ethoxycarbonyl)chinazolin‐4‐yloxy]‐ und (5,6,7,8‐Tetrahydro‐2‐phenylchinazolin‐4‐ylthio)alkansäure‐estern

Quinazolinecarboxylic Acids. Synthesis of Alkyl [2‐(Ethoxycarbonyl)‐3,4‐dihydro‐4‐oxoquinazolin‐3‐yl]‐, [2‐(Ethoxycarbonyl)quinazolin‐4‐yloxy]‐ and (5,6,7,8‐Tetrahydro‐2‐phenylquinazolin‐4‐ylthio)alkanoates The [(2‐aminobenzoyl)amino]alkanoic acids and their esters 1 showed a different reaction behaviour with diethyl oxalate. Compound 1 (n = 2,3) was converted into the quinazolinylalkanoates 3 . o ‐Aminohippurate yielded with ethyl (chloroformyl)formate a mixture of the amide 4 and the cyclized quinazolinone 7b . Ethyl 3,4‐dihydro‐4‐oxoquinazoline‐2‐carboxylate ( 6 ) reacted with 2‐bromoalkanoates, in the presence of NaH, to the [2‐(ethoxycarbonyl)‐3,4‐dihydro‐4‐oxoquinazolin‐3‐y1]acetates 7 in the case of alkyl bromoacetate, and to the O ‐alkylated derivatives 8 with the ethyl 2‐bromopropionate and ‐butyrate. 2‐Aminobenzamide ( 5 ) gave with ethyl 3‐(chloroformyl)‐2‐propenoate and methyl 3‐(chloroformyl)propionate the amides 9 or 11 , respectively, and not the expected quinazolinones. The cyclized product 12 was obtained from 11 and ethyl bromoacetate. Tetrahydroquinazolin‐4(3 H )‐thione 14 was synthesized by the reaction of 13 with NH 3 , and it was alkylated at the S‐atom with bromoalkanoates to 15 . The hydrazide 16 was synthesized from 15b with hydrazine hydrate.