Koelsch, C. F. et al. published their research in Journal of the American Chemical Society in 1950 | CAS: 1646-27-1

Methyl benzofuran-2-carboxylate (cas: 1646-27-1) belongs to benzofurans derivatives. Benzofuran is the “”parent”” of many related compounds with more complex structures. For example, psoralen is a benzofuran derivative that occurs in several plants. Introduction of benzofurans in organic synthesis, particularly drug synthesis, involves generally the use of their metalated species as nucleophiles in addition reactions or in metal-catalysed cross-coupling reactions.Reference of 1646-27-1

The internal Michael reaction. II. Formation of arylated coumarans, of an indoline, a dihydrothionaphthene, and a hydrocarbostyril was written by Koelsch, C. F.;Stephens, C. R. Jr.. And the article was included in Journal of the American Chemical Society in 1950.Reference of 1646-27-1 This article mentions the following:

Condensation of m-cresol and BzCH2CO2Et with 90% H2SO4 gives 25% 7-methyl-4-phenylcoumarin (I). Distilling 50 cc. from a mixture of 12 g. I in 50 cc. alc. and 50 cc. 10% NaOH with 15 g. ClCH2CO2Na (II) in 20 cc. water and treating the residue with 14 g. ClCH2CO2H and 14 g. NaOH gives after acidification 9.5 g. 4-methyl-β-phenyl-coumaric-O-acetic acid, m. 181-3° (from dilute AcOH); di-Me ester (III) m. 87-8°. Internal Michael condensation of III, effected by warming it to 60° with MeONa in MeOH solution, gives 80% Me 3-carbomethoxymethyl-6-methyl-3-phenyl-2,3-dihydrocoumarilate, b1 173-5°, m. 89-90° (from petr. ether); saponification gives the acid, m. 204-6°. This is the first known case of a Michael reaction in which the acceptor bears 2 aryl groups on its β-C atom. 3-Phenylcoumarin and II give α-phenylcoumaric-o-acetic acid, m. 197-8°, which on boiling with MeOH and H2SO4 gives a mono-Me ester, m. 144-5° (from MeOH), and a di-Me ester (IV), m. 72° (from petr. ether). IV (2.1 g.) with MeONa gives Me coumarilate (V), b2 130-40°, m. 54-5°, PhCH2CO2Me (VI), and 0.9 g. Me 3-(α-carbomethoxybenzyl)-2,3-dihydrocoumarilate (VII), b2 195-7°, m. 124-5° (from petr. ether), saponified to the acid, m. 162-3°. VII on heating with small amounts of NaOMe to 85-120° undergoes retrograde Michael reaction to V and VI. Boiling 25 g. 2,5-Cl(O2N)C6H3CHO, 75 cc. alc., 35 g. Na sarcosinate, 11.5 g. K2CO3, and a little Cu acetate gives N-(2-formyl-4-nitrophenyl)sarcosine (VIII), m. 149° (from dilute AcOH); 2,4-dinitrophenylhydrazone, m. 209-10°. Heating 3.5 g. VIII, 7 g. CH2(CO2H)2, 8 cc. pyridine, and 8 drops piperidine 2 h. to 100° gives 3.6 g. 2-methylamino-5-nitrocinnamic-N-acetic acid (IX), m. 211-12° (decomposition); Me ester (X), m. 79° (from ether). IX reduced with Fe and AcOH gives 5-amino-2-methylaminocinnamic-N2-acetic acid, m. 170°; Me ester-2HCl, m. 178-80°. Heating X with NaOMe gives Me 2-carbomethoxy-1-methyl-5-nitro-3-indoline acetate, b1.5 210-20°, saponified in dilute MeOH to the acid, m. 175-7° (decomposition). Also prepared was carbostyril-1-acetic acid, m. 267-8° (decomposition), o-(methylamino)cinnamic-N-acetic acid, m. 143-4°, 2-chloro-5-nitrocinnamic acid, m. 220-1° (decomposition). The dried diazosulfide obtained by treating diazotized o-aminocinnamic acid (XI) with HSCH2-CO2H, boiling with AcOEt, distilling to dryness, and treating the K2CO3 extract of the residue with acid gives on esterification di-Me o-mercaptocinnamate S-acetate, o-MeCO2CH: CHC6H4SCH2CO2Me (XII), b4 168-75°, m. 42-3°, also prepared by reducing (o-HO2CCH:CHC6H4S)2 with Zn and NaOH, followed by ClCH2CO2H. The free acid of XII m. 237-9°. XII with NaOMe gives Me 2-carobomethoxy-2,3-dihydro-3-thianaphtheneacetate, b4 160-2°, saponified to its acid, m. 143-4°, and traces of a water insoluble compound, C11H8O3S, m. 238-40° (anhydride of the acid?). Me o-aminocinnamate and PhCH2COCl give Me o-(phenylacetamido)cinnamate (XIII), m. 140° (from Me-Ph); free acid, m. 232-4°. XIII (1.4 g.) in 10 cc. MeOH boiled 2 h. with 0.5 g. NaOMe gives 1 g. Me 3-phenylhydrocarbostyril-4-acetate, m. 140-41.5°; free acid, m. 207-8°. Sarcosinenitrile added to a stirred mixture of iced 20% aqueous Na2CO3 and PhCH:CHCOCl in ether gives 87% N-cinnamoylsarcosinenitrile (XIV), m. 92-3°. XIV with MeOH and HCl gives Me N-cinnamoylsarcosinate (XV), b3 177-80°, m. 59-60°. XV gives no internal Michael reaction on treating with Na-OMe. o-Acetylallocinnamic acid (XVI), m. 143-4°, prepared by H5IO6 oxidation of 1-methyl-1,2-naphthoquinol, was esterified by treating its Ag salt with MeT. The XVI Me ester, m. 55-6°, on warming with NaOMe in MeOH gives no internal Michael reaction; an unidentified unsaturated acid, m. 181 5°, was obtained. In the experiment, the researchers used many compounds, for example, Methyl benzofuran-2-carboxylate (cas: 1646-27-1Reference of 1646-27-1).

Methyl benzofuran-2-carboxylate (cas: 1646-27-1) belongs to benzofurans derivatives. Benzofuran is the “”parent”” of many related compounds with more complex structures. For example, psoralen is a benzofuran derivative that occurs in several plants. Introduction of benzofurans in organic synthesis, particularly drug synthesis, involves generally the use of their metalated species as nucleophiles in addition reactions or in metal-catalysed cross-coupling reactions.Reference of 1646-27-1

Referemce:
Benzofuran – Wikipedia,
Benzofuran | C8H6O – PubChem