Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• -ketonitriles 16 with a substituted hydrazine in the presence of Et3N in ethanol under reflux conditions. The intermediate 16 was obtained from β-ketoester 15 on treatment with TFA, which in turn was synthesized by condensing 4-(phenylsulfonamidomethyl)cyclohexane carboxylic acid or benzoic acid 13

Shelf-stable electrophilic trifluoromethylating reagents: A brief historical perspective

• Norio Shibata,
• Andrej Matsnev and
• Dominique Cahard

Beilstein J. Org. Chem. 2010, 6, No. 65, doi:10.3762/bjoc.6.65

• Scheme 14. Reagent 18 was obtained as a 1:1 mixture of diastereoisomers originating from the chirality at the sulfur atom. The trifluoromethylation of a β-ketoester by 18 was then carried out in the presence of DBU to furnish the trifluoromethylated β-ketoester in 43% yield but as a racemate (Scheme 14

• dicyanoalkylidenes by S-(trifluoromethyl)benzothiophenium salts. Synthesis of chiral S-(trifluoromethyl)benzothiophenium salt 18 and attempt of enantioselective trifluoromethylation of a β-ketoester. Synthesis of O-(trifluoromethyl)dibenzofuranium salts. Photochemical O- and N-trifluoromethylation by 20b. Thermal O

Zeolite catalyzed solvent- free one-pot synthesis of dihydropyrimidin- 2(1H)-ones – A practical synthesis of monastrol

• Mukund G. Kulkarni,
• Sanjay W. Chavhan,
• Mahadev P. Shinde,
• Dnyaneshwar D. Gaikwad,
• Ajit S. Borhade,
• Attrimuni P. Dhondge,
• Yunnus B. Shaikh,
• Vijay B. Ningdale,
• Mayur P. Desai and
• Deekshaputra R. Birhade

Beilstein J. Org. Chem. 2009, 5, No. 4, doi:10.3762/bjoc.5.4

• monastrol, a potent inhibitor of kinesin Eg5. Keywords: Biginelli reaction; DHPMs; neat; MCR; zeolite; Introduction The Biginelli reaction is a well-known multicomponent reaction involving a one-pot cyclocondensation of an aldehyde, β-ketoester and urea/thiourea [1][2][3]. Multicomponent reactions (MCRs

Sordarin, an antifungal agent with a unique mode of action

• Huan Liang

Beilstein J. Org. Chem. 2008, 4, No. 31, doi:10.3762/bjoc.4.31

• (Scheme 9). The latter was directly converted to a β-ketoester by reaction with ethyl diazoacetate in the presence of SnCl2. A final Knoevenagel cyclization afforded substance 45. The enantioselective synthesis implemented an improved procedure that relied on alkylation of the metallohydrazone of 43 with

Synthesis of crispine A analogues via an intramolecular Schmidt reaction

• Ajoy Kapat,
• Ponminor Senthil Kumar and
• Sundarababu Baskaran

Beilstein J. Org. Chem. 2007, 3, No. 49, doi:10.1186/1860-5397-3-49

• 6 can be readily prepared from the β-ketoester 7, which in turn can be synthesized from the dimethoxybenzoic acid 8 as shown in Scheme 4.[30] 3,4-Dimethoxybenzoic acid (8) on treatment with paraformaldehyde in the presence of conc. H2SO4 followed by reduction with LAH gave the corresponding diol 9

• readily converted to the corresponding β-ketoester 7 via Dieckmann cyclization and the resultant product was purified by recrystallization using H2O-EtOH solvent system (Scheme 5). Our attempts towards the alkylation of β-ketoester 7 with 1-chloro-3-iodopropane under different reaction conditions were

• its analogues. Intramolecular Schmidt reaction of olefin azide. Retrosynthetic approach for crispine A analogues. Synthesis of β-ketoester 7. Alkylation of ketal-ester 12. Synthesis of azido-ketone 6. The intramolecular Schmidt cyclization of azido-ketone 6. Synthesis of acid analogue of crispine A