Organocatalytic Diastereoselective Synthesis of Diazoaryl-benzo[]azepine Derivatives.

To construct multisubstituted seven-membered nitrogenous heterocyclic scaffolds, an efficient method, employing 2-aminoaryl -monosubstituted hydrazones and 2-oxo-3-butenoates under Brønsted acid catalysis, has been developed. This strategy highlights the umpolung reactivity of 2-aminobenzaldehyde arylhydrazones toward 2-oxo-3-butenoates to afford ()-diazoaryl-benzo[]azepine derivatives in excellent yields (89-99%) and with high diastereoselectivities (>19:1 dr).

Organocatalytic synthesis of densely functionalized oxa-bridged 2,6-epoxybenzo[b][1,5]oxazocine heterocycles.

Metal-free addition of salicylhydrazones to electron deficient internal alkynes catalyzed by 1,4-diazabicyclo[2.2.2]octane (DABCO) to yield oxa-bridged 2,6-epoxybenzo[b][1,5]oxazocine heterocycles was achieved.

Regioselective carboannulation of electron-deficient allenes with dialkyl (2-formylphenyl)malonates leading to multisubstituted naphthalenes.

An efficient base-catalysed regioselective carboannulation of allenoates (or allenylphosphonates) with dialkyl 2-(2-formylphenyl)malonates that leads to multi-substituted naphthalenes in high yields has been developed. This cascade reaction proceeds through Michael addition, cyclisation, dealkoxycarboxylation and tautomerisation. By using an allenylphosphine oxide, a species analogous to one of the intermediate species in the mechanistic pathway has been isolated.