Alkylation of Pyrroles with Propargyl Halides

The interest in N-propargylpyrrole is motivated, in particular, by its application in the synthesis of diacetylene derivatives, which are promising for the preparation of highly ordered polymeric structures possessing specific optical, electronic, and magnetic properties [587,588], 

2-propargylpyrrole and N,2- andN,3-dipropargylpyrroles are isolated from the reaction mixture (preparative GLC), total yield of the side-products being about 12%. The same reaction in L1NH2/NH3 (Uq.) delivers N-propargylpyrrole in only 48%. In NaNH2/NH3 (liq.) (1 h), a mixture of N-propargylpyrrole and its allenic isomer (10 1) in 43% yield is formed. 

Allenylation of pyrrole with propargyl bromide proceeds easier than with propargyl chloride in the former case, calcinated KOH or additives (in the case of KOH O.5H2O) of t-BuOK are not required. N-Allenylpyrrole has been synthesized from pyrrole and propargyl bromide in 68% yield and 98% purity (2% of propargyl isomer) [592]. 

Before the works [590,591], N-allenylpyrrole was prepared by laborious two-stage protocol first, N-propargylpyrrole was synthesized from pyrrole and propargyl bromide in the system NaNH2/NH3 (liq.), and then acetylene-aUene isomerization in the presence of superbases KOH (t-BuOK)/DMSO [593] and NaNH2/Al203 [594] was carried out. 

Products of Pyrroles Alkylation by Functional Organic Halides 

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