One-Pot Synthesis of 3-Substituted 3,4-Dihydro-1,2,3-benzotriazine Derivatives Based on the Reaction of o-Bromobenzyl Azides with Butyllithium

• Published in: Helvetica chimica acta Vol. 99; no. 1; pp. 33 - 36
• Main Authors: Kobayashi, Kazuhiro, Chikazawa, Yuuki
• Format: Journal Article
• Language: English
• Published: Zürich WILEY-VCH Verlag 01.01.2016; WILEY‐VCH Verlag; Wiley; Wiley Subscription Services, Inc
• Subjects: 3,4‐Dihydro‐1,2,3‐benzotriazines; 3-benzotriazines; 4-Dihydro-1; Bromine/lithium exchange; Chemistry; Chemistry, Multidisciplinary; o-Bromobenzyl azides; o-Lithiobenzyl azides; Physical Sciences; Ring closure; Science & Technology; CYCLIZATION
• ISSN: 0018-019X; 1522-2675
• DOI: 10.1002/hlca.201500234

An efficient one‐pot procedure for the preparation of 3‐substituted 3,4‐dihydro‐1,2,3‐benzotriazines 2, 3, and 4 from o‐bromobenzyl azides 1 is described. The reaction of these azides with BuLi in THF at −78° generates o‐lithiobenzyl azides via the Br/Li exchange. These lithium compounds immediately undergo intramolecular cyclization to give the corresponding (dihydro‐1,2,3‐benzotriazinyl)lithium intermediates, which are trapped with a variety of acylating agents or BnBr at N(3) exclusively to provide the desired products in moderate to good yields.