Michael-type addition of azoles of broad-scale acidity to methyl acrylate

• Sławomir Boncel,
• Kinga Saletra,
• Barbara Hefczyc and
• Krzysztof Z. Walczak

Beilstein J. Org. Chem. 2011, 7, 173–178, doi:10.3762/bjoc.7.24

• retro-Michael reaction – in equilibrium with Michael-type addition. By contrast, DIPEA, with a lower pKa gave the same adducts 3a and 3b in excellent yields. For 1b (the azole with the lowest acidity) a similar yield to 1a was achieved only after a significantly prolonged reaction time due to its lower

• acrylate was observed. Nevertheless, decreased yields for azole adducts when DBU or NaH were used as catalysts at elevated temperature could originate from a reversibility of the Michael reaction since unreacted azoles were isolated. This observation is in a good agreement with our recent findings for

• Michael-type addition of uracils to acrylic acceptors [27][42], where a a strongly basic catalyst (DBU) enabled control of regioselectivity via a retro-Michael reaction. Conclusion We have developed and optimised a simple and effective synthetic protocol for Michael-type addition of azoles of broad-scale

A short synthesis of (±)-cherylline dimethyl ether

• Bhima Y. Kale,
• Ananta D. Shinde,
• Swapnil S. Sonar,
• Bapurao B. Shingate,
• Sanjeev Kumar,
• Samir Ghosh,
• Soodamani Venugopal and
• Murlidhar S. Shingare

Beilstein J. Org. Chem. 2009, 5, No. 80, doi:10.3762/bjoc.5.80

• followed by Pictet–Spengler cyclization. Keywords: Curtius rearrangement; Michael reaction; Pictet–Spengler cyclization; radical azidonation; Introduction Aryl-1,2,3,4-tetrahydroisoquinolines have attracted much attention from the synthetic community owing to the potential biological activities of this

Asymmetric reactions in continuous flow

• Xiao Yin Mak,
• Paola Laurino and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2009, 5, No. 19, doi:10.3762/bjoc.5.19

• flow. Asymmetric synthesis of ß-lactams. α-Chlorination of acid chlorides in flow. Asymmetric Michael reaction in continuous flow. Enantioselective addition of Et2Zn to benzaldehyde using monolithic chiral amino alcohol. Continuous-flow hydrolytic dynamic kinetic resolution of epibromohydrin (32

Efficient 1,4-addition of α-substituted fluoro(phenylsulfonyl)methane derivatives to α,β-unsaturated compounds

• G. K. Surya Prakash,
• Xiaoming Zhao,
• Sujith Chacko,
• Fang Wang,
• Habiba Vaghoo and
• George A. Olah

Beilstein J. Org. Chem. 2008, 4, No. 17, doi:10.3762/bjoc.4.17

• from 20% to 50%) efficiently promoted the Michael reaction. With 50 mol% catalyst loading, the reaction rates were approximately 2- to 3-fold faster than the corresponding 20 mol% PPh3 catalyzed reactions. A dramatic increase in the efficiency of the reaction came from the usage of less bulkier

• well as HRMS. In addition, base-sensitive functional groups such as cyano, nitro, and ester were well tolerated during the course of the reaction. The failure of (E)-pent-3-en-2-one to undergo the Michael reaction under these conditions demonstrates that the reaction is not tolerant of substituents at

A convenient allylsilane- N-acyliminium route toward indolizidine and quinolizidine alkaloids

• Roland Remuson

Beilstein J. Org. Chem. 2007, 3, No. 32, doi:10.1186/1860-5397-3-32

• ] two other syntheses were recently published. [40][41] The first steps of our synthesis were carried out as shown in Scheme 5. The starting material was ethyl 2-aminopropanoate 23. Chirality was introduced with isomers (R)-23a and (S)-23b, which were prepared by a Michael reaction according to Davies

One-pot synthesis of novel 1H-pyrimido[4,5-c][1,2]diazepines and pyrazolo[3,4-d]pyrimidines

• Dipak Prajapati,
• Partha P. Baruah,
• Baikuntha J. Gogoi and
• Jagir S. Sandhu

Beilstein J. Org. Chem. 2006, 2, No. 5, doi:10.1186/1860-5397-2-5

• starting material occurred. Although we could not isolate any intermediate from the reaction mixture a plausible mechanism for the formation of the products entails an initial Michael reaction of 1 to 2 followed by cyclodehydration possibly by a Bohlmann-Ratz type[32] reaction leading to a seven-membered