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Lithiation and Substitution of N′-(ω-Phenylalkyl)-N,N-dimethylureas

El-Hiti, Gamal, Smith, Keith and Alshammari, Mohammed 2012. Lithiation and Substitution of N′-(ω-Phenylalkyl)-N,N-dimethylureas. Synthesis (Stuttgart) 44 (3) , pp. 2013-2022. 10.1055/s-0031-1291008

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Abstract

Lithiation of N′-phenethyl-N,N-dimethylurea with three equivalents of tert-butyllithium in anhydrous tetrahydrofuran at -78 °C takes place on the nitrogen and on the side-chain of the CH2 next to the phenyl ring (α-lithiation). The 2-lithio isomer can be obtained via bromine-lithium exchange of N′-2-(2-bromophenyl)ethyl-N,N-dimethylurea using methyllithium followed by tert-butyllithium in tetrahydrofuran at -78 °C. The lithium reagents thus obtained react with various electrophiles to give the corresponding substituted derivatives in excellent yields. Lithiation of N′-(3-phenylpropyl)-N,N-dimethylurea takes place on the α-CH2 with tert-butyllithium at 0 °C. On the other hand, lithiation of N′-(4-phenylbutyl)-N,N-dimethylurea with tert-butyllithium at 0 °C takes place on one of the methyl groups of the urea unit.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Subjects: Q Science > QD Chemistry
Uncontrolled Keywords: N′-phenethyl-N,N-dimethylurea - side-chain lithiation - bromine-lithium exchange - electrophile - synthesis
Publisher: Georg Thieme Verlag
ISSN: 0039-7881
Date of First Compliant Deposit: 30 March 2016
Last Modified: 04 Jun 2017 04:16
URI: http://orca-mwe.cf.ac.uk/id/eprint/35737

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