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Synfacts 2013; 9(1): 0093
DOI: 10.1055/s-0032-1317743
Metal-Mediated Synthesis
© Georg Thieme Verlag Stuttgart · New York

Metalation of 2-Phenylethyldimethylamine under Mild Conditions

Contributor(s):
Paul Knochel
,
Andreas K. Steib
Unkelbach C, Rosenbaum HS, Strohmann C * Technische Universität Dortmund, Germany
Direct Benzylic Metalation of a Phenethylamine Derivative: Potassium as the Key to Both Generation and Stabilization of a ‘Labile Anion’.

Chem. Commun. 2012;
48: 10612-10614
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Publication History

Publication Date:
17 December 2012 (online)

 
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Key words

lithium - benzylic metalation - potassium

Significance

The direct benzylic metalation of 2-phenylethylamine derivatives suffers from β-elimination. The authors found that benzylic metalation of 2-phenylethyldimethylamine can be performed at –78 °C with a mixture of t-BuLi and t-BuOK. The metalated species was found to be stable up to –40°C.


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Comment

Interestingly, the metalation cannot be performed with a mixture of t-BuLi and t-BuOLi. Therefore, the potassium cation seems to be crucial for an efficient conversion. Theoretical and structural studies reveal that potassium is important for the lowering of the barrier of the initial deprotonation, as well as for stabilization of the labile anion.


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