Abstract
� 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim A rhodium(III)-catalyzed cycloaddition of N-tert-butoxycarbonylhydrazones with internal alkynes was developed. The reaction features a regioselective α-imino alkyl C(sp3)−H bond functionalization resulting in selective formation of highly functionalized NH-free pyrroles. Our studies showed that utilizing the N-tert-butoxycarbonyl (N-Boc) as the oxidizing directing group is critical for achieving the observed pyrrole formation versus the isoquinoline formation. To account for the pyrrole formation, we hypothesized that a prior tautomerization of the N-Boc-hydrazones to enamines should occur, followed by regioselective C(sp2)–H cleavage to form a putative five-membered rhodacycle. Subsequent coupling of the rhodacycle with the alkynes would afford the pyrrole products. (Figure presented.).
Original language | English |
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Pages (from-to) | 4067-4074 |
Number of pages | 8 |
Journal | Advanced Synthesis and Catalysis |
Volume | 358 |
Issue number | 24 |
DOIs | |
Publication status | Published - 1 Jan 2016 |
Keywords
- alkynes
- cycloaddition
- C–H activation
- nitrogen heterocycles
- rhodium
ASJC Scopus subject areas
- Catalysis
- Organic Chemistry