AbstractA milder, more regioselective and practical approach to C3 or O-alkylation reaction of 4-hydroxycoumarins has been established. Both 2H-[3,2-c] furocoumarins and 4-hydroxycoumarin vinyl ether derivatives could be efficiently prepared by alkylating 4-hydroxycoumarins with electron-deficient allenoates catalyzed by PPh3 and DBU, respectively. The reaction outcomes can be controlled by changing the catalysts, starting with the same reaction substrates. Possible reaction mechanisms have also been proposed

An efficient synthetic pathway to 1,3-diene-2-ol sulfonates involving the [3,3]-sigmatropic rearrangement of allenic alcohols with sulfonic acids under mild reaction conditions is described. These products can easily undergo reduction or transition-metal catalyzed cross-coupling reactions to yield a series of stereodefined multisubstituted 1,3-dienes.

The first Lewis acid-catalyzed intramolecular interrupted Nazarov cyclization of 1,4-pentadien-3-ols is described. Using FeBr3 as the catalyst, a series of new substituted cyclopenta[b]indoles was prepared—through a sequence of Nazarov cyclization, nucleophilic amination, and isomerization—with good yields and high diastereo- and regioselectivities. A similar catalytic process was also developed for the synthesis of structurally interesting spiro[indene-1,4′-quinoline]s.

The tricomponent Biginelli reaction and the tetracomponent Hantzsch reaction which share the same reaction modules (aldehyde and β-ketone ester) have been found compatible. Therefore, a series of copolycondensates containing both 1,4-dihydropyridine (1,4-DHP) and 3,4-dihydropyrimidin-2(1H)-one (3,4-DHPM) in the main chains via the simultaneous Hantzsch and Biginelli reactions have been facilely synthesized. The ratio of 1,4-DHP and 3,4-DHPM in the polymer congeners could be easily tuned by changing the feeding ratio of reactants, and the thermal properties of the obtained polymers are thereby adjusted. As the first attempt to prepare copolycondensate through the combination of two multicomponent reactions (MCRs), the current method revealed and utilized the interesting compatibility between MCRs, providing a new strategy to prepare multicomponent functional polymers.

The first Lewis acid-catalyzed intramolecular interrupted Nazarov cyclization of 1,4-pentadien-3-ols is described. Using FeBr3 as the catalyst, a series of new substituted cyclopenta[b]indoles was prepared—through a sequence of Nazarov cyclization, nucleophilic amination, and isomerization—with good yields and high diastereo- and regioselectivities. A similar catalytic process was also developed for the synthesis of structurally interesting spiro[indene-1,4′-quinoline]s.

An efficient synthetic pathway to 1,3-diene-2-ol sulfonates involving the [3,3]-sigmatropic rearrangement of allenic alcohols with sulfonic acids under mild reaction conditions is described. These products can easily undergo reduction or transition-metal catalyzed cross-coupling reactions to yield a series of stereodefined multisubstituted 1,3-dienes.