Synthesis of 4-Halo-3(2H)-furanones Using Intramolecular Cyclization of Sulfonium Salts

Abstract

A simple and efficient synthesis of 4-halo-3(2H)-furanones by halogenative intramolecular cyclization of sulfonium salts is described, which can expedite the production of a variety of 4-bromo- or 4-iodo-3(2H)-furanones, useful synthetic building blocks, in good to high yield under mild conditions.

Synthesis of 3(2H)‐Furanones: A Review

“…Subsequently an ester enolate 323 is generated by the regenerated DMAP which undergoes an intramolecular cyclization furnishing the 4‐halo‐5‐alkoxy‐3(2 H )‐furanone after the elimination of diphenyl sulfide. [ 67 ] The synthesized 4‐iodo‐5‐ethoxy‐3(2 H )‐furanone 318e was then subjected to different Pd‐catalyzed coupling reactions such as Suzuki, Sonogashira, and Stille coupling to introduce different substituents at the 4‐postion of the 3(2 H )‐furanone moiety (Scheme 70). [ 67 ]…”

“…[67] The synthesized 4-iodo-5ethoxy-3(2H)-furanone 318e was then subjected to different Pd-catalyzed coupling reactions such as Suzuki, Sonogashira, and Stille coupling to introduce different substituents at the 4-postion of the 3(2H)-furanone moiety (Scheme 70). [67] Scheme 70. Synthetic transformations of 4-halo-5-alkoxy-3(2H)-furanones 318.…”

Palladium-Catalyzed Oxidative Cyclization of α-Allenols in the Presence of TBN: Access to 3(2H)-Furanones

“…White solid, 77 mg, 74% yield; mp = 152−153 °C; R f = 0.4 (pet. ether/ ethyl acetate 80:20); 1 H NMR (500 MHz, CDCl 3 ) δ 7.92 (d,J = 7.6 Hz,2 H),7.87 (d,J = 8.2 Hz,2 H),7.65 (t,J = 7.4 Hz,1 H),7.53 (t,J = 7.8 Hz,2 H),7.29 (d,J = 8.1 Hz,2 H),2.41 (s,3 H), 1.44 (s, 6H); 13 C{ 1 H} NMR (126 MHz, CDCl 3 ) δ 198.3, 185.9, 144.5, 138.4, 133.7, 130.3, 129.6, 128.4, 128.3, 128.0, 115.9, 89.7, 23.0, 21.8; IR (CHCl 3 cm −1 ): υ 2943,1711,1599,1547,1476,1344,1154,1072,893,806,761,684 198.3, 185.9, 144.9, 144.4, 138.6, 130.4, 129.5, 129.0, 128.0, 125.5, 115.3, 89.5, 23.0, 21.9, 21.8; IR (CHCl 3 cm −1 ): υ 2924,1710,1609,1550,1495,1339,1159,1074,894,818,765,673; HRMS (ESI + ) m/z: 357.1155, found 357.1153-One (2c). White solid, 70 mg, 68% yield; mp = 126−127 °C; R f = 0.4 (pet.…”

“…White solid, 70 mg, 68% yield; mp = 126−127 °C; R f = 0.4 (pet. ether/ethyl acetate 80:20); 1 H NMR (500 MHz, CDCl 3 ) δ 7.90 (d,J = 9.1 Hz,2H),7.88 (d,J = 9.1 Hz,2H),7.38 (d,J = 8.1 Hz, 2 H), 7.29 (d, J = 7.9 Hz, 2 H), 3.00 (sept, J = 6.5 Hz, 1 H), 2.41 (s, 3 H), 1.42 (s, 6 H), 1.29 (d, J = 6.5 Hz, 6 H); 13 C{ 1 H} NMR (126 MHz, CDCl 3 ) δ 198.3, 185.8, 155.6, 144.4, 138.5, 130.6, 129.5, 128.0, 126.5, 125.8, 115.3, 89.4, 34.5, 23.7, 23.0, 21.8 . White solid, 56 mg, 54% yield; mp = 164−165 °C; R f = 0.3 (pet.…”

Alkylation Reactions with Alkylsulfonium Salts

“…21a In addition, halogenative intramolecular cyclization of 37 with NXS (X = Br, I) conveniently furnished a variety of 4-bromo- or 4-iodo-substituted 5-alkoxyfuran-3(2 H )-ones 42 as useful synthetic building blocks in good to high yields. 21c Acylative intramolecular cyclization of alkylsulfonium salts 44 by in situ formation of a mixed anhydride between carboxylic acid 43 and trifluoroacetic anhydride (TFAA) in the presence of N -methylimidazole, followed by sequential acylation and cyclization, was extensively explored, which provided various 2-substituted 4-oxo-4,5-dihydrofuran-3-carboxylates 45 in good yields (Scheme 8c ). 21d…”