949013-80-3Relevant academic research and scientific papers
The intramolecular Morita-Baylis-Hillman-type alkylation reaction
Cran, John W.,Krafft, Marie E.,Seibert, Kimberly A.,Haxell, Thomas F.N.,Wright, James A.,Hirosawa, Chitaru,Abboud, Khalil A.
experimental part, p. 9922 - 9943 (2012/02/05)
From the initial development of a homologous Morita-Baylis-Hillman reaction utilizing epoxides as electrophiles, the method was expanded to enable the exclusively organocatalyzed intramolecular allylation of enones and to develop the intramolecular MBH-type alkylation of activated alkenes. We successfully utilized both enones and unsaturated thioesters as the activated alkene component. This work, carried out using stoichiometric amounts of the trialkylphosphine, gave an array of functionalized five- and six-membered carbocycles in high yields. With the cycloalkylation of enones and thioesters, conditions that allowed the use of substoichometric amounts of the phosphine catalyst were developed. As a result both five- and six-membered rings can be formed efficiently with little to no loss in yield upon comparison to yields obtained when stoichiometric amounts of trialkylphosphines were employed. We isolated, for the first time, an MBH-type intermediate exhibiting unprecedented trans geometry of the phosphonium salt and acyl group.
Catalytic asymmetric 1,4-addition reactions using α,β- unsaturated N-acylpyrroles as highly reactive monodentate α,β- unsaturated ester surrogates
Matsunaga, Shigeki,Kinoshita, Tomotumi,Okada, Shigemitsu,Harada, Shinji,Shibasaki, Masakatsu
, p. 7559 - 7570 (2007/10/03)
Synthesis and application of α,β-unsaturated N-acylpyrroles as highly reactive, monodentate ester surrogates in the catalytic asymmetric epoxidation and Michael reactions are described. α,β-Unsaturated N-acylpyrroles with various functional groups were synthesized by the Wittig reaction using ylide 2. A Sm(O-i-Pr)3/H8-BINOL complex was the most effective catalyst for the epoxidation to afford pyrrolyl epoxides in up to 100% yield and >99% ee. Catalyst loading was successfully reduced to as little as 0.02 mol % (substrate/catalyst = 5000). The high turnover frequency and high volumetric productivity of the present reaction are also noteworthy. In addition, a sequential Wittig olefination-catatytic asymmetric epoxidation reaction was developed, providing efficient one-pot access to optically active epoxides from various aldehydes in high yield and ee (96→99%). In a direct catalytic asymmetric Michael reaction of hydroxyketone promoted by the Et 2Zn/linked-BINOL complex, Michael adducts were obtained in good yield (74-97%), dr (69/31-95/5), and ee (73-95%). This represents the first direct catalytic asymmetric Michael reaction of unmodified ketone to an α,β-unsaturated carboxylic acid derivative. The properties of α,β-unsaturated N-acylpyrrole are also discussed. Finally, the utility of the N-acylpyrrole unit for further transformations is demonstrated.
A convenient synthesis of N-acylpyrroles from primary aromatic amides
Ekkati, Anil R.,Bates, Dallas K.
, p. 1959 - 1961 (2007/10/03)
Synthesis of N-acylpyrroles in 45-85% isolated yield from primary aromatic amides and excess 2,5-dimethoxytetrahydrofuran in presence of one equivalent of thionyl chloride is reported. This method has several advantages including short reaction times, mild reaction conditions, and easy workup. The technique works particularly well for deactivated aromatic amides.
