a simple and green chemical procedure was reported for the synthesis of dihydropyrimidinones from various aldehydes, ethyl acetoacetate and urea or thiourea using  holmium chloride as catalyst. the reactions were performed under solvent free conditions with ultrasound irradiation as the energy source. the advantages of this protocol include the excellent yield, operational simplicity, short tim...

a  convenient  and  efficient  one-pot  four-component  synthesis  of  1,  2,  4,  5-tetrasubstituted  imidazoles  using  nano  tio2  as  a  recyclable  catalyst  is  reported.  the results  show  that  the  methodology  has  several  advantages  such  as  low  loading  of catalyst,  excellent  yield,  short  reaction  time,  operational  simplicity  and  solvent-free conditions.

a rapid and efficient one-pot, four-component protocol towards the synthesis of polyhydroquinoline derivatives has been developed. the condensation of aldehyde, dimedone, ethyl acetoacetate and ammonium acetate in presence of stannous chloride was carried out under solvent free condition to synthesize a variety of polyhydroquinoline derivatives in good to excellent yields. stannous chloride was...

an efficient green route for the preparation of naphthoxazinones, applying a three-component one-pot condensation reaction of 2-naphthol, aromatic aldehyde and urea in the presence of nano silica supported ferric chloride under solvent-free conditions has been developed. the present procedure offers several advantages such as short reaction time, simple workup, recovery and reusability of the c...

benzyltriphenylphosphonium bromide (btpb) has been applied as an efficient catalyst for the preparation of bis(indolyl)methanes (bims) via electrophilic substitution of indoles with aldehydes in the absence of solvent.

molybdate sulfuric acid (msa) has been prepared and used as catalyst for the biginelli synthesis of some quinazolinones/thiones under solvent-free conditions. the catalyst loading is low and it shows recyclability. this method has advantages such as avoidance of the organic solvents, high yield of pure products, short reaction times and operational simplicity.

an efficient synthesis of methyl 2-[2-(alkylimino)-4-oxo-3-phenyl-1,3-thiazolan-5-yliden]acetate derivatives via simple three-component reaction and one-pot reactions between isoquinoline, dimethyl acetylenedicarboxylate and n-phenylthiourea under solvent-free conditions without using any additional catalyst, is described. the mild reaction conditions and good yields and exhibit the synthetic a...

One-pot multicomponent condensation of β-naphthol, aromatic aldehydes, acetamide or urea in the presence of potassium hydrogen sulfate was carried out under solvent-free condition to afford amidoalkyl naphthols in 83%~96% yields.