Tetrazolverbindungen. 4 [1]. Alkylierung von 1‐Aryl‐5‐(2‐dimethylamino‐vinyl)‐1 H‐tetrazolen

Abstract

Tetrazole Compounds. 4. Alkylation of 1‐Aryl‐5‐(2‐dimethylamino‐vinyl)‐1 H‐tetrazoles Alkylation of 1‐aryl‐5‐(2‐dimethylamino‐vinyl)‐1 H‐tetrazoles 1 with dialkyl sulfates or alkyl iodides yields mainly 4‐alkyl‐1‐aryl‐5‐(2‐dimethylamino‐vinyl)‐1 H‐tetrazolium salts which can be isolated free from isomers by separation as perchlorates 2. The reaction proceeds with retention of the E configuration of the vinyl group. In contrast to 1 the methyl groups of the dimethylamino substituent in 2 are magnetically non‐equivalent indicating restricted rotation of this residue. On heating 2 with aqueous mineral acids the dimethylaminovinyl moiety undergoes degradation to a methyl group affording 4‐alkyl‐1‐aryl‐5‐methyl‐1 H‐tetrazolium salts 4, the structure of which was confirmed by independent synthesis. With hot aqueous alkali hydroxide 2 reacts under ring cleavage to give aryl azide. — 1H n.m.r. and u.v. spectroscopic data of the tetrazolium salts 2 and 4 are reported.

1,3- and 1,4-Substituted tetrazolium salts

“…Sometimes, individual salts 3 precipitate immediately. 14,22,25,32 This approach is largely used in the synthesis of 1,4-substituted tetrazolium salts (Table 1).…”

“…29 1,4,5-Trisubstituted tetrazolium salts 93a,b undergo N-dealkylation 98 or fragmentation in the presence of bases, 25,101 and ring-opening products always contain alkyl or aryl azide. 1,4,5-Trialkyltetrazolium salts 94 undergo deprotonation under the action of sodium hydride in tetrahydrofuran.…”

“…36 Boiling of 1-alkyl-4-aryl-5-(2-dimethylaminovinyl)tetrazolium perchlorates 104 in hydrochloric acid leads to the modification of the substituent at the C(5) atom. 25 Treatment of 3-acetylmethyl-1,5-dimethyltetrazolium chloride (105) with a nitrating mixture results in mesoionic tetrazole 106. 107 1,4,5-(107) and 1,3,5-trisubstituted tetrazolium salts (108) undergo cyclisation into 1H-and 2H-pyrrolotetrazoles 109 and 110 upon heating in acetic acid in the presence of sodium acetate.…”

“…3,5-Diaryl-1-methyltetrazolium salts 92 are resistant to the action of Et 3 N in toluene at 20 8C, but react vigorously with sodium ethoxide in benzene or toluene to yield a complex mixture of reaction products among which biaryls are predominant. 29 1,4,5-Trisubstituted tetrazolium salts 93a,b undergo N-dealkylation 98 or fragmentation in the presence of bases, 25,101 and ring-opening products always contain alkyl or aryl azide. 1,4,5-Trialkyltetrazolium salts 94 undergo deprotonation under the action of sodium hydride in tetrahydrofuran.…”