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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]

Abstract: The regioselective nitroso Diels–Alder (NDA) cycloadditions of 3-dienyl-2-azetidinones with nitrosobenzene to generate oxazine-substituted β-lactams in excellent yields are reported. The amidiolytic ring opening of the cycloadducts with sodium methoxide followed by iodocyclization using I2/K2CO3 etiquette to capitulate previously unknown, multisubstituted pyrroloxazine in outstanding yields is also accounted. [Copyright &y& Elsevier]

Abstract: A facile single step synthesis of novel azocinone derivatives involving tandem [2+2] cycloaddition and Cope rearrangement in the reactions of cross-conjugated azatrienes with vinyl/isopropenyl ketenes supported by theoretical calculations is reported. [Copyright &y& Elsevier]

We report a Pd-catalyzed intramolecular [3C + 2C + 2C] cycloaddition between alkylidenecyclopropanes, alkynes and alkenes. The method provides synthetically relevant 5-7-5 tricyclic structures, with good chemoselectivity and complete diastereoselectivity. [ABSTRACT FROM AUTHOR]

Highly diastereo- and π-facially selective imino Diels–Alder cycloadditions of 3-allylideneamino-2-azetidinones having stereocentres at its α- and β-positions, with symmetrical dienophiles leading to the formation of biologically potent (2-oxo-4-styrylazetidin-3-yl)–pyridine hybrids have been reported. [ABSTRACT FROM AUTHOR]

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]

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]

A nickel(0)-catalyzed intermolecular [3+2] cycloaddition of bis(alkylidenecyclopropanes) with diazenes such as diethyl or diisopropyl azodicarboxylate gave pyrazolidine-1,2-dicarboxylates in moderate to good yields (61–72%). [ABSTRACT FROM AUTHOR]

[3+2+2] Cycloaddition reactions are of key importance in organic chemistry for the synthesis of seven-membered mono- and condensed carbocycles. This review article summarises the different reports on transition-metal-catalysed [3+2+2] cycloaddition reactions since 2000. Different transitionmetals, such as Ni, Rh, Pd, Co, or Ru, which have been earlier reported for higher order [3+2+2] cycloaddition reactions are summarized in this article. The [3+2+2] cycloadditions of different functionalized substrates afford cycloheptane derivatives, 6-7,5-7 condensed bicyclic carbocycles, or 5-7-5 or 6-7-5 condensed tricyclic carbocycles. These higher order cycloaddition reactions may provide an easy route for the total synthesis of natural products, or as a preferable key synthetic step leading to final structure. [ABSTRACT FROM AUTHOR]

Acetylenic ester promoted ring opening of dienyl-thiazolidin- 4-ones and subsequent electrocyclization affords 5-phenyl-6-aryl pyridine-2-carboxylates in good to excellent yields. [ABSTRACT FROM AUTHOR]

The reactions of butadienylketene with variety of 1,4-diazabuta-1,3-dienes are studied. The reactions resulted in the formation of previously unknown functionalized cis butadienyl-4-iminomethyl-azetidin-2-ones and butenylidene-butadienyl-[2,2′-biazetidine]-4,4′- diones. Butadienyl ketene reacts in fashion with both iminic portion of 1,4- diazabuta-1,3-dienes and competitive [4+2] of 1,4-diazabuta-1,3-dienes as 4π component with butadienyl ketene as 2π component are not observed. [ABSTRACT FROM AUTHOR]

Tandem aza-Michael addition of 3-amino-2-azetidinones with acetylenic esters and subsequent intramolecular amidic ring opening of the initially formed azetidin-3-ylaminoprop- or -but-2-enoic ester is described. The reaction provides a facile route for the formation of functionalized 4-oxo-4,5-dihydro-1H-pyrroles in good yields. [ABSTRACT FROM AUTHOR]

Nickel catalyzed [3+2] cycloaddition reactions of bis(methylenecyclopropane) with cyclic and acyclic dienophiles have been explored. The reactions resulted in the formation of functionalized cyclopentanes in good yields. The reactions were also explored under microwave irradiation for the first time to yield [3+2] cycloadducts in short reaction time and high yields. [ABSTRACT FROM AUTHOR]

A Rh-catalyzed intramolecular [3+2+2] cycloaddition is reported. The cycloaddition affords synthetically relevant 5,7,5-fused tricyclic systems of type 2 from readily available dienyne precursors. The transformation takes place with moderate or good yields, high diastereoselectivity, and total chemoselectivity. [ABSTRACT FROM AUTHOR]

The reactions of in situ-generated butadienylketene with 1,4-diazabuta-1,3-dienes are studied. [ABSTRACT FROM AUTHOR]

The reactions of in situ-generated butadienylketene with 1,4-diazabuta-1,3-dienes are studied. [ABSTRACT FROM AUTHOR]

The cycloaddition reactions are performed under conventional heating conditions or microwave irradiation to form cyclopentane derivatives. [ABSTRACT FROM AUTHOR]

leading to 5,7,5-fused tricyclic systems [ABSTRACT FROM AUTHOR]