Synthesis of pyrimidine derivatives using N-bis(methylthio)methylenecyanamide

N-Bis(methylthio)methylenecyanamide ( 1 ) was allowed to react with active methylene compounds (methyl cyanoacetate, dimethyl malonate, ethyl acetoacetate, ethyl phenylacetate) in the presence of potassium carbonate or potassium hydroxide in dimethyl sulfoxide followed by the treatment using appropriate a base or an acid to give the corresponding 6-methylthiouracil derivatives in 15–80% yields. These uracil derivatives are found to be useful intermediates for the synthesis of 6-aminouracils and fused pyrimidine derivatives.     

First synthesis of 1,9-dideoxyforskolin from ptychantin A

1,9-Dideoxyforskolin 2 has been synthesized starting from ptychantin A 3.     

Diastereoselective preparation and characterization of ruthenium bis(bipyridine) sulfoxide complexes

A new concept in the synthesis of optically active octahedral ruthenium complexes was realized for the first time when cis- or trans-Ru(bpy)2Cl, (cis- or trans-1) was reacted with either (R)-(+)- or (S)-(-)-methyl p-tolyl sulfoxide (2 or 3); this novel asymmetric synthesis leads to the diastereoselective formation of the ruthenium bis(bipyridine) complex cis-delta-[Ru(bpy)2(2)Cl]Cl (4) (49.6% de) or cis-lambda-[Ru(bpy)2(3)Cl]Cl (5) (48.4% de), respectively. cis- or trans-Ru(dmbpy)2Cl2 (cis- or trans-6) (dmbpy = 4,4'-dimethyl-2,2'-bipyridine) also reacts with 2 or 3, leading to the diastereoselective formation of cis-delta-[Ru(dmbpy)2(2)Cl]Cl (7) (59.5% de) or cis-lambda-[Ru(dmbpy)2(3)Cl]Cl (8) (57.2% de), respectively. The diastereoselectivity of these reactions is governed solely by the chirality of the sulfoxide nucleophile. This represents the first process by which a sigma-bonded ligand occupying only a single coordination site has had such an important influence on the stereochemical outcome of a ruthenium bis(bipyridine) complex formation. These novel complexes were fully characterized by elemental analysis and IR, UV/vis, and 1H, 13C, and 2D NMR spectroscopy. An investigation into the chiroptical properties of these novel ruthenium bis(bipyridine) sulfoxide complexes has been carried out, and circular dichroism spectra are used to assign absolute stereochemistry.     

Palladium-catalyzed aminoallylation of activated olefins with allylic halides and phthalimide

The three-component aminoallylation reaction of the activated olefins 2 with the phthalimide 1a and allyl chloride proceeded very smoothly in the presence of Pd(2)dba(3).CHCl(3) (5 mol %)/P(4-FC(6)H(4))(3) (40 mol %) and Cs(2)CO(3) (3 equiv against 2) in dichloromethane at room temperature to give the corresponding aminoallylated products, N-pent-4-enylphthalimides 3, in 58-99% yields. The reaction of oxazolidinone 1b also proceeded very smoothly to give N-(2,2-dicyano-1-phenylpent-4-enyl)oxazolidinone in a quantitative yield; however, the Tsuji-Trost-type allylation products 4 were obtained in the case of dibenzylamine, N-tosylaniline, and pyrrolidin-2-one. Further, 2 underwent cycloaddition with N-tosylvinylaziridine 9a in the presence of Pd(2)dba(3).CHCl(3) (5 mol %)/P(4-FC(6)H(4))(3) (40 mol %) in THF at room temperature, giving the corresponding pyrrolidines 11 in 69-99% yields.     

Novel [2 + 2] photocycloaddition-induced rearrangement of bichromophoric naphthalene-tethered resorcinol ethers

The first examples of sequential photocycloaddition-rearrangement reactions of naphthalene-tethered resorcinol ethers are described. Bichromophoric aromatic compounds with naphthalene and resorcinol ether moieties were irradiated in the presence/absence of a small amount of acid to give the corresponding cycloaddition-rearrangement products. From the determination of quantum yields, steady-state fluorescence spectral studies, and fluorescence lifetime measurements, the mechanism of this novel photoinduced multistep reaction was elucidated to involve the initial intramolecular exciplex formation, followed by the intramolecular [2 + 2] photocycloaddition between the two aromatic rings and the subsequent acid-catalyzed skeletal rearrangement of the resulting cyclobutane derivative leading to the final products.