Synthesis of functionalized chromans by PnBu3-catalyzed reactions of salicylaldimines and salicylaldehydes with allenic ester.

P(n)Bu(3)-catalyzed cyclization reactions of salicylaldimines and salicylaldehydes with ethyl 2,3-butadienoate gave the corresponding functionalized chromans in moderate to good yields in THF under mild conditions. The new reaction provides a new method for the synthesis of biologically active chroman products.

Phosphine-catalyzed tandem reaction of allenoates with nitroalkenes.

A P(p-FC(6)H(4))(3)-catalyzed tandem reaction between ethyl 2,3-butadienoate and nitroalkenes has been developed, which involves a [3 + 2] cycloaddition and a subsequent umpolung addition. The asymmetric version of this tandem reaction has also been investigated by using chiral phosphanes.

Beyond the aza-Morita-Baylis-Hillman reaction: Lewis base-catalyzed reactions of N-Boc-imines with ethyl 2,3-butadienoate.

Lewis base catalyzed reactions of N-Boc-imines and ethyl 2,3-butadienoate were investigated systematically. The normal aza-Morita-Bylis-Hillman products were obtained in good to excellent yields catalyzed by DABCO. When PPh(3) was used as the catalyst, novel rearrangement product (E)-ethyl 2-((Z)-(tert-butoxycarbonylimino)(aryl)methyl)but-2-enoates could be formed in moderate yields.

Phosphine-mediated [3+2] cycloaddition reactions of ethyl 5,5-diarylpenta-2,3,4-trienoates with arylmethylidenemalononitriles and N-tosylimines.

Ethyl 5,5-diarylpenta-2,3,4-trienoates were synthesized and utilized in the phosphine-mediated [3+2] cycloaddition reactions with arylmethylidenemalononitriles and N-tosylimines in the presence of tributylphosphine. These reactions provide an easy access to a variety of novel polysubstituted cyclopentenes or pyrrolidines in good to excellent yields under mild conditions.

A convenient three-component reaction leading to the synthesis of polysubstituted cyclohexene derivatives.

A three-component reaction of beta-nitrostyrene, arylmethylidenemalononitrile and malononitrile catalyzed by imidazole produced the corresponding polysubstituted cyclohexene derivatives in moderate to good yields under mild conditions. A further improvement of this three-component reaction has also been achieved by starting from a commercially available aromatic aldehyde, nitromethane and malononitrile to give the products in moderate yields.