A new synthesis of benzo[b]thiophenes utilizing an interrupted Pummerer reaction

Bond-Forming and -Breaking Reactions at Sulfur(IV): Sulfoxides, Sulfonium Salts, Sulfur Ylides, and Sulfinate Salts

“…In 2009, Kobayashi et al. utilized interrupted Pummerer reactions to access a range of substituted benzothiophene derivatives from the corresponding sulfoxide precursors (Scheme a). , …”

Synthesis of 3-Arylthieno[2,3-b]-, -[2,3-c]- or -[3,2-c]pyridines Utilizing an Interrupted Pummerer Reaction

“…7 Thus, 4a was dissolved in excess acetic anhydride and the solution was heated at 100 °C until complete consumption of the starting material 4a (TLC analyses). The reaction was, however, complicated by the competing normal Pummerer reaction and reduction of the sulfoxide moiety to give a complex mixture containing the desired 3-phenylthieno [2,3-b] This result led us to investigate the reaction of the substrate carrying electron-rich (hetero)aryl groups 4b-e. (2-Chloropyridin-3-yl)(4-methoxyphenyl)methanone (1b) was prepared as described for the preparation of 1a.…”

“…2e, 6 On the other hand, we have recently reported a synthesis of 3-arylbenzo [b]thiophenes by means of an interrupted Pummerer reaction of 1-(arylethenyl)-2-(ethylsulfinyl)benzenes. 7 Hence, we were interested in developing a new method applicable to the preparation of all of these three types of thienopyridine derivatives by applying this procedure to the respective pyridine substrates. The results of our study, which provide a convenient and common approach to these thienopyridines, are reported here.…”

Concise Synthesis of 3-Acetoxy-N,N-dialkylbenzo[b]thiophene-2-carboxamides from 2-Ethylsulfanylbenzoates

“…We have recently described the synthesis of 3-arylbenzo [b]thiophenes by an interrupted Pummerer reaction of 2-ethylsulfinyl-a-arylstyrenes; the sulfoxides are heated in acetic anhydride at 100 °C to give the 3-arylbenzo[b]thiophenes in reasonable yields. 1 In this paper, we wish to report that the interrupted Pummerer reaction of N,N-dialkyl-3-(2-ethylsulfinylphenyl)-3-oxopropanamides, which can be easily prepared in two step from 2-sulfanylbenzoates, provides a concise route for the preparation of 3-acetoxy-N,N-dialkylbenzo[b]thiophene-2-carboxamides. Several methods for the preparation of 3-hydroxybenzo[b]thiophene-2-carboxic acid ester derivatives have already been reported 2 due to their biological utilities.…”

“…5:5). IR (neat): 3360, 1683, 1643, 1605, 1022 cm -1 1. H NMR (500 MHz): d = 1.27 (t, J = 7.3 Hz, 1.5 H), 1.31 (t, J = 7.3 Hz, 1.5 H), 2.68-2.79 (m, 1 H), 3.01 (s, 1.5 H), 3.08 (br s, 4.5 H), 3.14-3.23 (m, 1 H),3.99 (d, J = 15.6 Hz, 0.5 H), 4.15 (d, J = 15.6 Hz, 0.5 H), 5.64 (s, 0.5 H), 7.56 (d, J = 2.3 Hz, 0.5 H), 7.61 (dd, J = 8.2, 2.3 Hz, 0.5 H), 7.78 (dd, J = 8.2, 2.3 Hz, 0.5 H), 8.02 (d, J = 1.8 Hz, 0.5 H), 8.09 (d, J = 8.2 Hz, 0.5 H), 8.24 (d, J = 8.2 Hz, 0.5 H), 10.88 (br s, 0.5 H).…”