Selective synthesis of functionalized pyrroles from 3-aza-1,5-enynes

Abstract

2-Trifluoromethyl-5-(arylsulfonyl)methyl pyrroles and 2-trifluoromethyl-4-(arylsulfonyl)methyl pyrroles were selectively synthesized from trifluoromethyl-substituted 3-aza-1,5-enynes via a cyclization/sulfonyl group migration cascade catalyzed by AgOOCCF3 and CsOPiv, respectively. Alkylvinyl-substituted pyrroles were generated from seven-atom skeleton 3-aza-1,5-enynes via aryl sulfinic acid elimination in the presence of Cs2CO3. Two ion-pair intermediates were proposed and a key intermediate, aza-diene-yne, was successfully isolated in the mechanistic studies.

Recent Advances on Pyrrole Synthesis through Different Annulation Modes

“…Using similar type of substrates, Wan and Xin et al [30] achieved the selective synthesis of 2-trifluoromethyl-5-(arylsulfonyl)methyl pyrroles and 2-trifluoromethyl-4-(arylsulfonyl)methyl pyrroles from trifluoromethylsubstituted 3-aza-1,5-enynes via a cyclization/sulfonylmigration cascade using AgOOCCF 3 and CsOPiv as catalyst, respectively (Scheme 8). Additionally, alkylvinylsubstituted pyrroles could be obtained from the substrates with an ester group at the position of CF 3 group through aryl sulfinic acid elimination under the promotion of Cs 2 CO 3 .…”

Recent Advances for the Synthesis of N‐Unsubstituted Pyrroles

“…Later, [35] the same group of scientists applied cyclization/sulfonyl group migration cascade for the synthesis of diverse NH‐pyrroles catalyzed not only by Cs 2 CO 3 , but also by AgOOCCF 3 and CsOPiv. The use of AgOOCCF 3 and CsOPiv provides selectively formation of 2‐trifluoromethyl‐5‐(arylsulfonyl)methyl pyrroles 104 and 2‐trifluoromethyl‐4‐(arylsulfonyl)methyl pyrroles 105 from trifluoromethyl‐substituted 3‐aza‐1,5‐enynes 102 , respectively (Scheme 34).…”

“…Wan et al [34] examined a base-catalyzed (Cs 2 CO 3 as a base) selective cycloisomerization of 3-aza-1,5-enynes 102, which Later, [35] the same group of scientists applied cyclization/ sulfonyl group migration cascade for the synthesis of diverse NH-pyrroles catalyzed not only by Cs 2 CO 3 , but also by AgOOCCF The different pathway was studied for 3-aza-1,5-enynes 102 in the presence of Cs 2 CO 3 . Alkyvinyl-substituted pyrroles 106 were obtained from 7-atoms skeleton of 3-aza-1,5-enynes (Scheme 34).…”

N-Propargylic β-enaminocarbonyls: powerful and versatile building blocks in organic synthesis

“…10 Recently, the same authors applied this methodology to synthesis of a series of 2-triuoromethyl-5-(arylsulfonyl)methyl pyrroles and 2-triuoromethyl-4-(arylsulfonyl)methyl pyrroles from corresponding triuoromethyl-substituted N-propargylic b-enaminoesters. 11 The groups of Wan also were able to demonstrate that a series of sulfonyl vinyl-substituted pyrroles 23 could be obtained from the corresponding phenoxysubstituted N-propargylic b-enaminoesters 22 employing 20 mol% of Cs 2 CO 3 as catalyst in anhydrous DMF (Scheme 9). The reaction proceeds along the similar mechanistic pathway that described in Scheme 4a to afford intermediate A.…”