Keith Smith, G. El‐Hiti, M. Alshammari
Oct 9, 2013
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Influential Citations
17
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Journal
Synthesis
Abstract
Lithiation of N -(pyridin-3-ylmethyl)pivalamide, tert -butyl N -(pyridin-3-ylmethyl)carbamate, and N , N -dimethyl- N ′-(pyridin-3-ylmethyl)urea with tert -butyllithium (3 equiv) in anhydrous tetrahydrofuran at –78 °C takes place on the nitrogen and on the ring at the 4-position. The dilithium reagents thus obtained react with various electrophiles to give the corresponding substituted derivatives in high yields. On the other hand, regioselective side-chain lithiation occurs with lithium diisopropylamide (3.3 equiv) at –20 to 0 °C. A mixture of ring and side-chain substitution products is obtained with n -butyllithium as the lithium reagent. Treatment of one of the ring-substituted products with trifluoroacetic anhydride in dichloromethane under reflux conditions led to formation of the corresponding 1 H -pyrrolo[3,4- c ]pyridine in high yield.