Metal-Free Domino One-Pot Decarboxylative Cyclization of Cinnamic Acid Esters: Synthesis of Functionalized Indanes

Abstract

Trifluoroacetic acid promoted unprecedented domino reaction for the synthesis of diverse indanes starting from simple cinnamic acid esters is described. Their formation can be explained via acid triggered decarboxylation of cinnamic acid esters and subsequent inter/intramolecular cyclization. Overall process involves in the intramolecular cleavage of two σ-bonds (C-O and C-C) and inter/intramolecular construction of two/one C-C σ-bond(s). Significantly, this protocol was successful without the aid of any metal salts.

Microwave‐Assisted Domino Heck Cyclization and Phosphorylation: Synthesis of Phosphorus Containing Heterocycles

“…It is worth noting that these sorts of experimental procedures have already been published elsewhere. [10a], [10b], …”

“…We believe that there is no report using a domino Heck and phosphorylation strategy for the synthesis of fused bicyclic heterocycles containing phosphoryl moiety. In our efforts in developing synthetic domino transformations using transition‐metal catalysis,[10a], [10b], we envisaged that palladium catalyzed intramolecular Heck coupling and intermolecular phosphorylation of ortho ‐aryl allyl ethers/ ortho ‐arylenamides/ ortho ‐aryl allylamines would be feasible to furnish phosphorylated heterocyclic products. Herein, we present the microwave‐assisted tandem Heck and phosphorylation strategy for the construction of 3,3′‐disubstituted dihydrobenzofurans and oxindoles possessing a phosphoryl group.…”

Selective Formation of Internal Olefinic Trimer of α-Methylstyrenes with HI Gas and Ketones

“…Colorless oil; 1 H NMR (CDCl 3 , 400 MHz): δ 1.03 (s, 3H), 1.31 (s, 3H), 1.66 (s, 3H), 2.17 (d, J = 13.0 Hz, 1H), 2.36 (d, J = 12.9 Hz, 1H), 3.77 (s, 3H), 3.78 (s, 3H), 6.62 (d, J = 2.5 Hz, 1H), 6.78 (diffused d, J = 8.9 Hz, 2H), 6.84 (dd, J = 2.5 and 8.3 Hz, 1H), 7.09 (d, J = 8.4 Hz, 1H), 7.10 (diffused d, J = 8.9 Hz, 2H). 5…”

“…Colorless solid; mp 116–117 °C; 1 H NMR (CDCl 3 , 300 MHz): δ 1.40 (s, 3H), 1.45 (s, 3H), 2.08 (s, 3H), 2.36 (d, J = 13.5 Hz, 1H), 2.47 (d, J = 13.5 Hz, 1H), 7.09 (ddd, J = 1.3, 7.0, and 8.3 Hz, 1H), 7.21 (dd, J = 1.9 and 8.6 Hz, 1H), 7.29 (ddd, J = 1.1, 6.7, and 8.1 Hz, 1H), 7.37 (d, J = 8.7 Hz, 1H), 7.40–7.48 (m, 3H), 7.65 (d, J = 8.7 Hz, 1H), 7.75–7.85 (m, 5H). 5…”

“…2,3 However, it succeeded in the reaction with HI/I 2 as an initiator in liquid SO 2 because dormant (C–I-bonded compound) is activated by I 2 to form cationic species. 4 The indane was obtained as a main product from the reaction of α-methylstyrene with trifluoroacetic acid, 5 whereas other acids 6−8 resulted mainly in three compounds: 2,4-diphenyl-4-methyl-1-pentene, 2,4-diphenyl-4-methyl-2-pentene, and 1,1,3-trimethyl-3-phenylindane. Other conditions with acidic ionic liquids, 9,10 molecular sieves, 11 acidic ion-exchange resins, and clays 8 also resulted in indane as a main product.…”