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The manuscript describes an efficient, atom economical synthesis of pyrimido[4,5-b][1,4]benzodiazepin-4-ones by relatively unexplored 7-endo-trig Pictet–Spengler type cyclisations. The synthetic methdodlogy involves the synthesis of different variants of 5-arylidene-amino-3H-pyrimidines and their p-toluene sulfonic acid mediated 7-endo-trig Pictet–Spengler type cyclisations to afford biologically relavent functionalized benzodiazepine condensed pyrimidinones such as pyrimido[4,5-b][1,4]benzodiazepines in good to excellent yields (82–94%). [ABSTRACT FROM AUTHOR]

3-Butadienyl-β-lactams are useful organic synthon which have efficiently been explored for the synthesis of a variety of heterocyclic systems. The present review compiles the various reports on the synthesis of 3-butadienyl-β-lactams and their explorations in the development of variety of monocyclic as well as condensed heterocyclic systems. [ABSTRACT FROM AUTHOR]

Rhodium-catalyzed intermolecular [3 + 2+2] cycloaddition reactions of bis(methylenecyclopropanes) with different alkynes are described. The rhodium-catalyzed [3 + 2+2] cycloadditions resulted in the formation of functionalized 5–7–3 spirocyclic carbocycles in moderate yields with excellent regio- and chemo-selectivity. [ABSTRACT FROM AUTHOR]