cyclization of 5‐alkenylthiazolones and ketimines that allows the assembly of three diastereoisomers through the combination of stereodivergent organocatalysis and the following diastereoselective transformation of products. A broad spectrum of pyrrolidinylspirooxindoles featuring stereochemical diversity has been synthesized through organocatalytic formal1,3‐dipolarcycloadditions with up to 98%
We report a highly chemo- and diastereoselective [3 + 2] cyclization of vinylethylene carbonates and 5-alkenyl thiazolones through palladium catalysis. The previously inert aza-thioester moiety on the thiazolone substrates is reacted selectively with the zwitterionic pi-allylpalladium species. A variety of amide monothioacetals (AMTA) with two quaternary stereocenters are facilely synthesized. An additional spirocyclic quaternary stereocenter could be further installed by Rh-catalyzed metal-carbene insertion into the C-S bond on the AMTA moiety in a highly stereoselective manner.
Phosphine-Catalyzed Annulations Based on [3+3] and [3+2] Trapping of Ketene Intermediates with Thioamides
With the aim of developing novelannulationsvia ketene intermediates, allenyl imide and alkynoates bearing good leaving groups are used for their function in a tandem conjugate addition–elimination reaction (SN2′ type) promoted by nucleophilic phosphine catalysts. By utilizing thioamides as 1S,3N-bis-nucleophiles, [3+3] and [3+2] annulations have been established to allow rapid access to 1,3-thiazin-4-ones
A Brønstedbase-catalyzedtandem [2+4] annulation/tautomerization/aromatization reaction of α-alkylidene succinimides with 5-alkenyl thiazolones has been developed for synthesis of functionalized thiazolo pyrones under mild conditions. The prepared thiazolo pyrones show fluorescent properties.