Giorgio Molteni1, Alessandro Ponti2. 1. Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy. 2. Istituto di Scienze e Tecnologie Chimiche "Giulio Natta" (SCITEC), Consiglio Nazionale delle Ricerche, via Golgi 19, 20133 Milano, Italy.
Abstract
The site- and regio-selectivity of thermal, uncatalysed 1,3-dipolar cycloadditions between arylazides and mono- or tetra-substituted allenes with different electronic features have been investigated by both conceptual (reactivity indices) and computational (M08-HX, ωB97X-D, and B3LYP) DFT approaches. Both approaches show that these cycloadditions follow a nonpolar one-step mechanism. The experimental site- and regio-selectivity of arylazides towards methoxycarbonyl- and sulfonyl-allenes as well as tetramethyl- and tetrafluoro-allenes was calculated by DFT transition state calculations, achieving semiquantitative agreement to both previous and novel experimental findings. From the mechanistic standpoint, 1H-NMR evidence of a methylene-1,2,3-triazoline intermediate reinforces the reliability of the computational scheme.
The site- and regio-selectivity of thermal, uncatalysed 1,3-dipolar cycloadditions between arylazides and n class="Chemical">mono- or tetra-substituted allenes with different electronic features have been investigated by both conceptual (reactivity indices) and computational (M08-HX, ωB97X-D, and B3LYP) DFT approaches. Both approaches show that these cycloadditions follow a nonpolar one-step mechanism. The experimental site- and regio-selectivity of arylazides towards methoxycarbonyl- and sulfonyl-allenes as well as tetramethyl- and tetrafluoro-allenes was calculated by DFT transition state calculations, achieving semiquantitative agreement to both previous and novel experimental findings. From the mechanistic standpoint, 1H-NMR evidence of a methylene-1,2,3-triazoline intermediate reinforces the reliability of the computational scheme.
Entities:
Keywords:
1,3-dipolar cycloaddition; M08-HX; allene; azide; local softness
Authors: Karen L Schuchardt; Brett T Didier; Todd Elsethagen; Lisong Sun; Vidhya Gurumoorthi; Jared Chase; Jun Li; Theresa L Windus Journal: J Chem Inf Model Date: 2007-04-12 Impact factor: 4.956