Thermodynamic adduct

Kinetic and Thermodynamic Adducts Formed by Quinone Methides... 

Amination of naphthyridines can be carried out under kinetic or thermodynamic conditions <83AHC(33)95>, for example treatment of 1,5-naphthyridine (1) with KNH2—NH3 gives addition at C-2 (kinetic adduct) at —40°C, and addition at C-4 (thermodynamic adduct) at 10°C. 

The position of fastest addition to quinohnium salts is C-2, but with reversible reactions, a thermodynamic adduct with the addend at C-4 and the residual double bond in conjugation with the nitrogen, can be obtained. ... 

The standard Chichibabin amination of quinoline with sodium amide in DMA gives 2-aminoquinoline in a low 7% yield and 2-amino-3,4-dihydroquinoline in a 24% yield. Not until the introduction of the Chichibabin oxidative amination variant (e.g., in the presence of KMn04) were these yields improved. Regio-chemical outcome depends on reaction temperature (kinetic or thermodynamic control). 2-aminoquinoline (39) forms at -65 °C, i.e., the kinetic adduct, and is isolated in a 50-55% yield with no evidence of 4-amino adduct formation, whereas 4-aminoquinoline (40) forms in 60-65% yield at 15 °C, i.e., the thermodynamic adduct (oxidant added at -45 C), with 6-7% of 39. Substituted quinolines give various... 

We discuss here a number of cycloadditions, which probably proceed via polar intermediates. Reactions are described in Scheme 15. The additions of chlorosulphonyl isocyanate indicate the possibility of reversible formation of a kinetic adduct [e.g. (54)] which via a dipolar species can equilibrate to a thermodynamic adduct [e.g. (55)]. The precise nature of a product depends upon solvent, reaction time, and temperature, but by suitable choice of conditions high yields are possible. Various transformation products of (56), available in low yields, are described and the further transformation of (56) into (57) is noted. In contrast to V-nitrosoaziridines, (57) is thermally stable. 

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