Palladium-Catalyzed Asymmetric (3 + 2) Cycloaddition of 5-Allenyloxazolidine-2,4-Diones with Barbiturate-Derived Alkenes: Synthesis of Spirobarbiturate-γ-Lactams

Abstract

The 5-allenyloxazolidine-2,4-diones had been synthesized as novel precursors of π-allyl palladium zwitterion and were applied in a palladium-catalyzed enantioselective (3 + 2) annulation by using barbiturate-derived alkenes as the reaction partner in the presence of an axially chiral phosphoramidite ligand. This reaction proceeded smoothly under mild reaction conditions, affording highly functionalized spirobarbiturate-γ-lactam derivatives in excellent yields along with high diastereo-and enantioselectivities. The scale-up reaction and further transformation of the product were also successful.

Palladium-Catalyzed [5 + 4] Cycloaddition of 4-Vinyl-4-Butyrolactones with N-Tosyl Azadienes: Construction of Nine-Membered Ring

“…Mp = 207−208 °C. 1 H NMR (500 MHz, CDCl 3 ) δ 7.55−7.52 (m, 1H), 7.49 (d,J = 8.3 Hz,2H),7.39 (d,J = 7.6 Hz,1H),3H), 7.13 (dd, J = 5.0, 1.9 Hz, 3H), 7.01−6.92 (m, 2H), 6.90−6.85 (m,2H), 6.83 (d, J = 8.1 Hz, 2H), 6.76 (dt, J = 10.0, 2.1 Hz, 1H), 6.31 (dd, J = 9.5, 7.0 Hz, 1H), 4.87 (dd, J = 15.3, 7.0 Hz, 1H), 4.04−3.85 (m, 2H), 3.48 (s, 3H), 2.75 (ddd, J = 9.2, 6.8, 3.6 Hz, 1H), 2.68−2.59 (m, 2H), 2.19 (s, 3H). 13 C{ 1 H} NMR (126 MHz, CDCl 3 ) δ 171.3,162.0 (C−F, 3 J C−F = 247.1 Hz), 153.…”

“…Mp = 209−210 °C. 1 H NMR (500 MHz, CDCl 3 ) δ 7.63−7.59 (m, 1H), 7.55 (d,J = 8.2 Hz,2H),1H),7.31 (dtd,J = 18.1,7.3,1.2 Hz,2H),5H),6H),6.34 (dd,J = 9.5,7.0 Hz,1H),4.94 (dd,J = 15.2,7.0 Hz, 1H), 4.12−3.95 (m, 2H), 3.85 (s, 3H), 3.54 (s, 3H), 2.90−2.79 (m, 1H), 2.79−2.66 (m, 2H). 13 C{ 1 H} NMR (126 MHz, CDCl 3 ) δ 172.2, 154.…”

“…Mp = 175−176 °C. 1 H NMR (500 MHz, CDCl 3 ) δ 7.61 −7.47 (m, 7H), 7.43−7.34 (m, 3H), 7.32−7.18 (m, 5H), 7.09 (dd, J = 4.9, 1.9 Hz, 3H), 6.92−6.85 (m, 2H), 6.81 (d, J = 7.9 Hz, 2H), 6.39 (dd, J = 9.4, 7.0 Hz, 1H), 4.89 (dd, J = 15.2, 7.0 Hz, 1H), 4.01 (d,J = 3.6 Hz,1H),3.97 (dd,J = 15.2,9.5 Hz,1H),3.47 (s,3H), 2.87−2.79 (m, 1H), 2.77−2.60 (m, 2H), 2.16 (s, 3H). 13 C{ 1 H} NMR (126 MHz, CDCl 3 ) δ 172.…”

4-Vinylbenzodioxinones as a new type of precursor for palladium-catalyzed (4+3) cycloaddition of azomethine imines

“…The precursors for the formation of π-allylpalladium zwitterionic intermediates play a critical role in the cycloaddition reactions, affecting the reactivity, cycloaddition types and structure of the cycloadducts. A variety of precursors with diverse structures have been reported, such as vinyl lactones, 7 methylidene lactones, 8 vinyl cyclic carbamates, 9 methylidene cyclic carbamates, 10 vinyl cyclic carbonates, 11 methylidene cyclic carbonates, 12 vinyl lactams 13 and acyclic carbonates. 14 Among them, cyclic carbamates 9,10 and cyclic carbonates 11,12 are usually used for the synthesis of functionalized azaheterocycles and oxa-heterocycles (Scheme 1a).…”

“…Although several types of cyclic carbonates such as allenyl cyclic carbonates, vinyl cyclic carbonates and methylidene cyclic carbonates have been reported, to the best of our knowledge, the benzo-fused cyclic carbonates have never been developed for the generation of an oxygen-containing π-allylpalladium precursor. In this context, based on our experiences in designing and developing new π-allylpalladium precursors and exploration on cycloaddition reactions, 7,11 p ,13,14 g we merge the characteristics of both cyclic carbonates and vinyl benzoxazinanones to design and synthesize 4-vinylbenzodioxinones as a novel type of precursor of π-allylpalladium zwitterionic intermediates (Scheme 1b). With the use of 4-vinylbenzodioxinones, we herein developed a palladium-catalyzed (4+3) cycloaddition with C , N -cyclic azomethine imines, producing various benzoxadiazepine derivatives (Scheme 1b).…”