Solvent-Free One-Pot Synthesis of Sulfonephthaleins from Saccharin and Phenols

Sulfonephthaleins can be synthesized in a single pot from saccharin and phenol via the in situ formation of 2-sulfobenzoic anhydride, followed by its reaction with phenol using H₂SO₄ as the condensing agent, in the absence of any solvent. This solvent-free synthesis is more economical and environmentally benign.     

Simple and efficient synthesis of thysanone methyl ether

The synthesis of thysanone methyl ether is achieved by employing semivioxanthin methyl ether, which in turn is prepared by the tandem Michael addition of an anion of orsellinate to a substituted dihydropyrone.     

A General Method for the Synthesis of 11-Deoxyanthracyclinones

A general method for the synthesis of 11-deoxyanthracyclinones is described.     

Enantiomeric separation of novel anticancer agent 5-hydroxy-3-(4-methoxyphenyl)-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one

The enantiomers of 5-hydroxy-3-(4-methoxyphenyl)-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one, a novel anticancer agent, were separated by derivatisation with caronaldehyde, separation of the resulting diastereoisomers of the corresponding esters by silica gel column chromatography and regeneration of alcohols (S)-5-hydroxy-3-(4-methoxyphenyl)-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one and (R)-5-hydroxy-3-(4-methoxyphenyl)-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one under aqueous conditions. The absolute configuration of the enantiomers was determined by 1H NMR studies of the corresponding Mosher esters. Alternatively, the enantiomers were separated by preparative HPLC to collect the (S)- and (R)-5-hydroxy-3-(4-methoxyphenyl)-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-ones with high purity which was comparable with that obtained by the chemical method. The details of these methods have been presented herein.     

Reaction of substituted alkynols with alkoxycarbene complexes of chromium: a facile synthesis of substituted α,β-unsaturated-γ-butyrolactones

Substituted α,β-unsaturated-γ-butyrolactones, were synthesized from Fischer chromium carbenes and substituted alkynols in a two-step sequence. This method demonstrates a novel and mild route for the synthesis of this class of molecules.     

Unusual,selective, reductive,deoxygenation of cyclopentenone alcohols

A selective, reductive, deoxygenation of 2-aryl-4-hydroxycyclopent-2-en-1-ones to afford 2-aryl-cyclopent-2-en-1-ones was achieved by NaBH₄–CeCl₃ in methanol.     

Cross‐Coupling between Hydrazine and Aryl Halides with Hydroxide Base at Low Loadings of Palladium by Rate‐Determining Deprotonation of Bound Hydrazine

Reported here is the Pd‐catalyzed C–N coupling of hydrazine with (hetero)aryl chlorides and bromides to form aryl hydrazines with catalyst loadings as low as 100 ppm of Pd and KOH as base. Mechanistic studies revealed two catalyst resting states: an arylpalladium(II) hydroxide and arylpalladium(II) chloride. These compounds are present in two interconnected catalytic cycles and react with hydrazine and base or hydrazine alone to give the product. The selectivity of the hydroxide complex with hydrazine to form aryl over diaryl hydrazine was lower than that of the chloride complex, as well as the catalytic reaction. In contrast, the selectivity of the chloride complex closely matched that of the catalytic reaction, indicating that the aryl hydrazine is derived from this complex. Kinetic studies showed that the coupling process occurs by rate‐limiting deprotonation of a hydrazine‐bound arylpalladium(II) chloride complex to give an arylpalladium(II) hydrazido complex.     

A convenient approach to the total synthesis of (±) 4-demethoxydaunomycinone

A convenient and most practical approach to the synthesis of (±) 4-demethoxydaunomycinone starting from 2-methylhydroquinone is described.     

One-step preparation of α-chlorostyrenes

α-Chlorostyrenes were prepared via a one-step method involving Friedel-Crafts reaction of various aromatic substrates with acid chlorides in the presence of a heterogeneous Si-Fe catalyst.