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The general procedure for the synthesis of 6-iodobenzodihydropyran-2-one from hydrogenated cinnamic acid lactone was carried out as follows, with reference to literature [41] for the synthesis. In a flame-dried and argon flushed 250 cm3 two-necked round-bottomed flask equipped with a dropping funnel and an argon inlet, 5.00 g of dihydrocoumarin (15, 33.8 mmol) was dissolved in 35 cm3 dichloromethane (DCM). ICl (5.48 g, 33.8 mmol) dissolved in 35 cm3 DCM was slowly added through a dropping funnel over 15 min. The reaction was fully converted (after 20 h) and the reaction mixture was diluted with 100 cm3 DCM and washed with 0.1 M Na?S?O? solution (2 × 50 cm3). The combined aqueous phases were re-extracted with DCM (2 × 50 cm3). The combined organic layers were washed with saturated NaCl solution (1 × 200 cm3), dried over MgSO?, filtered, and the solvent was removed in vacuum. Recrystallization by DCM/cyclohexane (1/4) afforded 8.28 g (90% yield) of the product in the form of a colorless powder.16 The melting point was determined to be 134-136°C (133-134°C reported in the literature [37]); the nuclear magnetic resonance (NMR) data were in agreement with that described in the literature [41].

[1] Monatshefte fur Chemie, 2016, vol. 147, # 3, p. 509 - 521
[2] Journal of Organometallic Chemistry, 1990, vol. 387, # 3, p. 381 - 390