One-pot preparation of substituted pyrroles from α-diazocarbonyl compounds

• Fernando de C. da Silva,
• Mauricio G. Fonseca,
• Renata de S. Rianelli,
• Anna C. Cunha,
• Maria C. B. V. de Souza and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2008, 4, No. 45, doi:10.3762/bjoc.4.45

• quantity of rhodium(II) acetate in the presence of butyl vinyl ether to produce the corresponding 3-carbonyl-dihydrofurans 4–6. The rhodium catalyzed reaction of the α-diazocarbonyl compounds 1–3 was monitored by TLC chromatography. Evaporation of the solvents at the end of these reactions followed by

• straightforward route to construct variously substituted compounds of this class starting from readily available precursors. Experimental Analytical grade solvents were used. Butyl vinyl ether was freshly distilled before being used. Column chromatography was performed on silica gel 60 (Merck 70–230 mesh

• solution of the diazodicarbonyl compound (1–3, 2 mmol) in 5 mL of freshly distilled butyl vinyl ether was slowly added by a syringe pump, at a rate of 1.0 mL/h, to a stirred suspension of dirhodium tetraacetate (0.2 mmol) in 5.0 mL of the same butyl vinyl ether as solvent, under a nitrogen atmosphere. The

Vinylogous Mukaiyama aldol reactions with 4-oxy-2-trimethylsilyloxypyrroles: relevance to castanospermine synthesis

• Roger Hunter,
• Sophie C. M. Rees-Jones and
• Hong Su

Beilstein J. Org. Chem. 2007, 3, No. 38, doi:10.1186/1860-5397-3-38

• under acid conditions with CAN to give lactam 10 in 82% yield with retention of the MOM groups (Scheme 4). The vinyl ether 10 was then converted to a ketal in order to preclude any epimerization occurring at C-4, and this was achieved by subjecting 10 to bromine in the presence of methanol to give

Multiple hydride reduction pathways in isoflavonoids

• Auli K. Salakka,
• Tuija H. Jokela and
• Kristiina Wähälä

Beilstein J. Org. Chem. 2006, 2, No. 16, doi:10.1186/1860-5397-2-16

• discrepancies, notably in the δ value (8.69) reported for the H-8 which is some 2 δ units in excess of what would be expected for such a vinyl ether proton. Thus more work is required to fully confirm the nature of this class of reduction products. In the event, in our studies the reduction of isoflavone 1a by

An efficient synthesis of novel pyrano[2,3-d]- and furopyrano[2,3-d]pyrimidines via indium- catalyzed multi- component domino reaction

• Dipak Prajapati and
• Mukut Gohain

Beilstein J. Org. Chem. 2006, 2, No. 11, doi:10.1186/1860-5397-2-11

• Knoevenagel/hetero-Diels-Alder reaction of 1,3-dimethyl barbituric acid with an aromatic aldehyde and ethyl vinyl ether/2,3-dihydrofuran in presence of 1 mol% of indium(III) chloride. The reaction also proceeds in aqueous media without using any catalyst, but the yield is comparatively less (65–70

• reaction of α,β-ethylenic ketones and ethyl vinyl ether or 2,3-dihydrofuran has remained unexplored.[11] Herein, we report the first example of indium(III) chloride catalysed synthesis of fused pyrimidine derivatives via a multicomponent domino Knoevenagel hetero Diels-Alder reaction. The reaction proceeds

• ], we have investigated a new, simple and efficient synthesis of novel fused pyrimidines based on inverse electron-demand Diels-Alder reaction using ethyl vinyl ether/dihydrofuran and α,β-ethylenic ketones formed in situ as heterodienes in presence of 1 mol% of indium(III) trichloride (Scheme 1). This