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NBS‐Mediated Oxygen Transfer Reaction of Carbonyl in Ester: Efficient Synthesis of Benzil– o ‐carboxylate Derivative From o ‐Alkynylbenzoate
Author(s) -
Yuan SiTian,
Wang YanHua,
Liu JinBiao,
Qiu Guanyinsheng
Publication year - 2017
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201700168
Subject(s) - chemistry , benzil , electrophile , annulation , carboxylate , regioselectivity , nucleophile , derivative (finance) , ring (chemistry) , medicinal chemistry , stereochemistry , organic chemistry , catalysis , financial economics , economics
Abstract A neighbouring ester group‐participated diketonization of o‐alkynylbenzoate is described here for the synthesis of benzil‐o‐carboxylate. Application of the resulting benzil‐ o ‐carboxylate in the synthesis of quinoxalines is also reached from o‐alkynylbenzoate in an one‐pot fashion. This diketonization proceeds smoothly with a high regioselectivity under mild conditions. Importantly, neighbouring group plays an important role in diketonization. A plausible mechanism suggests that a bromo‐incoporated isocoumarin cation is described as an intermediate, and the whole process is constituted by NBS‐mediated electrophilic 6‐ endo annulation and oxygen transfer reaction through NBS‐mediated oxidative ring‐opening. Water serves as a nucleophile of ring‐opening.