Pyrimido azepines synthesis

L. El Kaim, L. Grimaud, J. Oble, J. Org. Chem. 2007, 72, 5835-5838. New Ugi-Smiles-metathesis strategy toward the synthesis of pyrimido azepines. 

Several condensed 5-nitropyrimidine derivatives have also been prepared from appropriate nitro-containing precursors. 2-Nitromethylene hexahydro-azepine (127) forms an adduct with benzoyl isothiocyanate which, during recrystallization from acetic acid, cyclizes to the pyrimido[3,4-a] azepine 128 (Scheme 25).119 This seems to be the only example of the use of a type 2 synthon for the synthesis of a 5-nitropyrimidine. 

The formation of amidines from lactim ethers and amines proceeds readily with high yields,8, >18,21,70-70 e.g., in the synthesis of imidazo-[l,2-6]azepine derivatives reported by Stolle et al.77 (Scheme 9), and in the preparation of the pyrimido[l,2-a]-azepine derivative (Scheme 10).70... 

In the first part of the section on the pyrimido[l,2-a]azepines, the chemistry of 2,3,4,6,7,8,9,10-octahydropyrimido[l,2-a]azepine (8) (generally called diazabicyclo[5.4.0] undec-7-ene, or DBU) is treated in a separate subsection, since DBU has proved to be a useful reagent in synthetic organic chemistry and an important catalyst in the synthesis of macromolecules. Since the appearance of two early reviews (72S591 75MI5), the applications of DBU have rapidly increased because of its favorable nonnucleophilic, yet strongly basic, properties. It can therefore be applied for the preparation of even relatively sensitive molecules. Following this, the synthesis, reactions, physicochemical properties, and briefly the applications of further pyrimido[l,2-a]azepine derivatives are discussed. The treatment of the chemistry of the other pyrimidoazepines (2-5 and 7) follows an essentially identical pattern to that for the pyrimido[l,2-a]azepines. 

Yamamoto et al. studied the synthesis and reactivities of pyrimido-[4,5-d]azepines (71BCJ153 77BCJ453 78H275). 

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See also in sourсe #XX -- [ , , , ]

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