Synthesis and reactivity of 2-thionoester pyrroles: a route to 2-formyl pyrroles

Min Joon Kim; Sophie M Gaube; Michael H R Beh; Craig D Smith; Alison Thompson

doi:10.1039/c9ra07527e

Synthesis and reactivity of 2-thionoester pyrroles: a route to 2-formyl pyrroles

RSC Adv. 2019 Oct 7;9(54):31773-31780. doi: 10.1039/c9ra07527e. eCollection 2019 Oct 1.

Authors

Min Joon Kim¹, Sophie M Gaube¹, Michael H R Beh¹, Craig D Smith¹, Alison Thompson¹

Affiliation

¹ Department of Chemistry, Dalhousie University P. O. Box 15000 Halifax NS B3H 4R2 Canada Alison.Thompson@dal.ca.

Abstract

2-Functionalised pyrroles exhibit considerable synthetic utility. Herein, the synthesis and reactivity of 2-thionoester (-C(S)OR) pyrroles is reported. 2-Thionoester pyrroles were synthesised using a Knorr-type approach from aliphatic starting materials. 2-Thionoester pyrroles were reduced to the corresponding 2-formyl pyrroles, or the deuterated formyl variant, in one step using RANEY® nickel, thereby removing the need for the much-utilised hydrolysis/decarboxylation/formylation steps that are typically required to convert Knorr-type 2-carboxylate pyrroles into 2-formyl pyrroles. 2-Thionoester pyrroles proved tolerant of typical functional group interconversions for which the parent 2-carboxylate pyrroles have become known.