Organocatalytic Stereoselective [8+2] Cycloaddition of Tropones with Azlactones

Recommended Tests for the Self-Disproportionation of Enantiomers (SDE) to Ensure Accurate Reporting of the Stereochemical Outcome of Enantioselective Reactions

“…For other examples of high-quality experimental work on organo-catalytic and transition metal-catalyzed reactions, other recent papers [136,137] also stand out.…”

“…As an exception, we are pleased to note the recent work by Prof. Eusebio Juaristi [ 135 ], which serves as an example of how high-quality organo-catalytic research should be performed and reported. For other examples of high-quality experimental work on organo-catalytic and transition metal-catalyzed reactions, other recent papers [ 136 , 137 ] also stand out.…”

Asymmetric organocatalytic sulfenylation for the construction of a diheteroatom-bearing tetrasubstituted carbon centre

“…In addition, when sulfenylated azlactone 6a was treated with TMSCl using methanol as the solvent at room temperature, an a-sulfur-substituted a-amino ester 13 could be obtained in 83% yield with 75% ee (Scheme 3c). According to the X-ray crystal structures of the chiral guanidineamide series, 9,12 previous density functional theory (DFT) calculations 13 and NMR analysis as well (see ESI †), we proposed that the optimal guanidine acted as a bifunctional organocatalyst containing one base and two hydrogen bonds. In connection with the absolute configuration of the product, 10 we rationalized the catalytic mode for this asymmetric sulfenylation.…”

“…According to the X-ray crystal structures of the chiral guanidine-amide series, 9,12 previous density functional theory (DFT) calculations 13 and NMR analysis as well (see ESI†), we proposed that the optimal guanidine acted as a bifunctional organocatalyst containing one base and two hydrogen bonds. In connection with the absolute configuration of the product, 10 we rationalized the catalytic mode for this asymmetric sulfenylation.…”

Tandem [5 + 1]/[8 + 2] cycloaddition reactions involving phosphiranes and tropones: facile access to 6,5,7-fused tricyclic skeletons

“…2 These higher-order cycloadditions often suffer from poor chemo-selectivity since different pericyclic reactions may occur with extended π-systems. Tropone, for example, has been reported to react as a 2π component in [2 + 4] 3 cycloadditions, a 4π component in [4 + 2] 4 and [4 + 6] 5 cycloadditions, a 6π component in [6 + 3] 6 and [6 + 4] 7 cycloadditions, and an 8π component in [8 + 2] 8 cycloadditions. It is highly desirable to be able to perform periselective reactions for synthetic applications.…”