160334-80-5Relevant academic research and scientific papers
Allene-Based Gold-Catalyzed Stereodivergent Synthesis of Azapolycyclic Derivatives of Unusual Structure
Alcaide, Benito,Almendros, Pedro,Martín-Montero, Raúl,Ruiz, M. Pilar
supporting information, p. 1469 - 1477 (2016/05/19)
The present study provides insights into the manner in which the configuration of β-aminoallene precursors affects their gold-catalyzed cyclization reactions. The reactivity can be switched by using indolizidinone-tethered β-aminoallenes bearing the syn- or the anti-disposition of both protons at the α- and β-allenic stereocenters. Fused heterocycles (seven examples, 60-75% yields) are obtained from the syn-precursors, while a dimerization-aminoketalization-spirocyclization sequence to afford benzo[b]pyrrolo[3,2,1-ij][1,7]naphthyridin-1-ones (four examples, 34-48% yields) can be achieved starting from their anti-isomers.
Facile conversion of 2-azetidinones to 2-piperidones: Application to a formal synthesis of Prosopis and Cassia alkaloids
Lee, Hyeon Kyu,Chun, Jong Soo,Pak, Chwang Siek
, p. 6445 - 6454 (2007/10/03)
Nonracemic 5,6-disubstituted 2-piperidones were prepared from readily accessible 3,4-disubstituted-2-azetidinones having pre-installed substituents by reductive ring opening of 2-azetidinones followed by stereoselective installation of Z-α,β-unsaturated ester and lactam formation. For the synthetic application to the naturally occurring piperidine alkaloids, such as Prosopis and Cassia alkaloids, 5-hydroxy-2-piperidones (+)-13 and (-)-24 were prepared from 2-azetidinones (-)-6b and (+)-18 via two-carbon ring homologation.
Facile transformation of 3,4-disubstituted 2-azetidinones to chiral 5,6-dihydro-2-pyridones
Lee, Hyeon Kyu,Chun, Jong Soo,Pak, Chwang Siek
, p. 3483 - 3486 (2007/10/03)
Chiral 5,6-disubstituted-5,6-dihydro-2(1H)-pyridones were prepared efficiently from readily accessible 3,4-disubstituted-2-azetidinones having preadjusted substituents and stereochemistry through the reductive ring opening of 2-azetidinones followed by Z-selective installation of acetate moiety and re-cyclization to 2-pyridones.
Base-promoted isomerization of cis-4-formyl-2-azetidinones: Chemoselective C4-epimerization vs rearrangement to cyclic enaminones
Alcaide, Benito,Aly, Moustafa F.,Rodriguez, Carolina,Rodriguez-Vicente, Alberto
, p. 3453 - 3459 (2007/10/03)
Two simple, efficient, and complementary methods for the regiospecific C4-epimerization of cis-4-formyl-2-azetidinones 1-3 are described. The first method uses 40% aqueous dimethylamine as reagent in heterogeneous medium with benzene at room temperature, in the presence of benzyltributylammonium bromide (3-4 mol %) as the phase-transfer catalyst. This transformation tolerates alkyl, alkenyl, alkynyl, aryl, and alkoxy substituents at the C3 of the 2-azetidinone ring. However, limitations of this isomerization are as follows: (i) only N-(p-methoxyphenyl)-β-lactams can be used, and (ii) transformation is less compatible with heteroatomic substituents bonded to the C3 position of the 2-azetidinone ring. A highly general solution to these problems relies on the use of sodium carbonate as the isomerization reagent in different solvents. We also describe a novel base-promoted rearrangement of the β-lactam ring to cyclic enaminones 6 and 21, involving an E1cB-elimination reaction in cis-4-formyl-2-azetidinones.
