Novel Synthesis of Carbapenam by Intramolecular Attack of Lactam Nitrogen toward η¹-Allenyl and η³-Propargylpalladium Complex

Abstract

When a THF solution of beta-lactam having propargyl phosphate was warmed in the presence of 5 mol % of Pd(2)(dba)(3) x CHCl(3), 20 mol % of a bidentate ligand, and sodium acetate (1.5 equiv) at 40 degrees C for 22 h, carbapenam was produced in high yield. In this reaction, the lactam nitrogen attacked the central carbon of a eta(3)-propargylpalladium complex, which was formed from propargyl phosphate and Pd(0).

Highly Regioselective Synthesis of Spirocyclic Compounds by a Palladium‐Catalyzed Intermolecular Tandem Reaction

“…Chemie to generate an allenylpalladium complex 5; [13,14] b) regioselective intramolecular nucleophilic attack of the carbanion to form intermediate 4 a; c) oxidative addition of the aryl halide to the palladium(0) catalyst; d) the addition of arylpalladium compounds to 1,2-dienes produces p-allylpalladium compounds; [15] and e) regioselective intramolecular nucleophilic attack [14] at the more hindered site to afford products 3. [16] The selectivity is presumably due to electronic effects [8a, 9c] at the benzylic position.…”

“…We have also investigated the reactions of substrates having various leaving groups. The reactions of propargyl carbonate 1 b, propargyl acetate 1 c and propargyl benzoate 1 d gave the desired products 3 a in moderate yields ( Table 2, entries [12][13][14]. In addition, propargyl phosphate 1 e also gave the product 3 a in a 62 % yield and shorter reaction time was required ( Table 2, entry 15).…”

Pd(0)‐catalyzed polycondensation of aryl‐substituted propargylic carbonates with bifunctional nucleophiles promoted by aryl group on the acetylenic terminal carbon

“…1,2 Many of the reports on the reactions describe the synthesis of heterocyclic compounds. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Sinou and coworkers [19][20][21][22] reported a palladiumcatalyzed condensation reaction of propargylic carbonates and catechol for the synthesis of 1,4-benzodioxins. When the reaction was performed with methyl-substituted carbonates 1a and 2a, the same product was obtained in 95% yield [Scheme 1(a)].…”

One‐Pot Synthesis of Highly Substituted Allenylidene Derivatives via Palladium‐ or Nickel‐Catalyzed Tandem Michael Addition–Cyclization Reaction

“…It has been found that other amines, such as benzylamine, naphthalen-2-amine and furan-2-amine were also well tolerated under our conditions (entries 10 and 12). We have also investigated the reactions of substrates with various leaving groups, such as propargyl acetate 1b, propargyl benzoate 1c and propargyl acetate 1d afforded the desired products 3a in good yields (entries [13][14][15].…”

“…(i) Decarboxylation of propargylic compound 1 catalyzed by Pd (0) generates an allenylpalladium complex 4 [13] or the Ni(II) species coordinates with the alkyne triple bond of 1 to afford 6. (ii) Base mediates a Michael addition which affords intermediate 5 or 7, respectively.…”