Premium
1,2,4‐Triazine vs. 1,3‐ and 1,4‐Oxazinones in Normal‐ and Inverse‐Electron‐Demand Hetero‐Diels–Alder Reactions: Establishing a Status Quo by Computational Analysis
Author(s) -
Rooshenas Parham,
Hof Kira,
Schreiner Peter R.,
Williams Craig M.
Publication year - 2011
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201001365
Subject(s) - chemistry , triazine , cycloaddition , computational chemistry , diene , inverse , density functional theory , status quo , stereochemistry , medicinal chemistry , catalysis , organic chemistry , mathematics , natural rubber , geometry , economics , market economy
We present an analysis of the well‐known normal‐ and inverse‐electron‐demand hetero‐Diels–Alder reaction involving 1,2,4‐triazine, 1,3‐oxazin‐6‐one, and 1,4‐oxazin‐2‐one, with alkenes and alkynes, utilizing density functional theory (DFT) at the SCS‐M P 2/cc‐pVDZ//B3LYP/6‐31G(d) level to establish a theoretical status quo for synthetic practioners regarding the relative reactivities and stereochemical outcomes for these useful heterocycles. The results suggest that in the unsubstituted cases 1,2,4‐triazine is less reactive in comparison to 1,3‐oxazin‐6‐one and 1,4‐oxazin‐2‐one for both reaction modes, whereas the cycloaddition regioselectivities depend largely on the diene. For example, 1,3‐oxazin‐6‐one leads to kinetic meta isomers, in comparison to 1,2,4‐triazine and 1,4‐oxazin‐2‐one, which give rise to para isomers.