Иодирование по Шульгину.

Из ПиХКАЛ.

A mixture of 7.4 g phthalic anhydride and 9.05 g of 2,5-dimethoxyphenethylamine (see the recipe for 2C-H for its preparation) was heated with an open flame. A single clear phase was formed with the loss of H2O. After the hot melt remained quiet for a few moments, it was poured out into a crystallizing dish yielding 14.8 g of a crude solid product. This was recrystallized from 20 mL CH3CN, with care taken for an endothermic dissolution, and an exothermic crystallization. Both transitions must be done without haste. After filtration, the solids were washed with 2x20 mL hexane and air dried to constant weight. A yield of 12.93 g of N-(2-(2,5-dimethoxyphenyl)ethyl)phthalimide was obtained as electrostatic yellow crystals, with a mp of 109-111 deg C. A sample recrystallized from IPA was white, with a mp of 110-111 deg C. Anal. (C18H17NO4) C,H,N.

To a solution of 12.9 g N-(2-(2,5-dimethoxyphenyl)ethyl)phthalimide in 130 mL warm (35 deg C) acetic acid which was being vigorously stirred, there was added a solution of 10 g iodine monochloride in 40 mL acetic acid. This was stirred for 1 h, while being held at about 30 deg C. The reaction mixture was poured into 1500 mL H2O and extracted with 4x75 mL CH2Cl2. The extracts were pooled, washed once with 150 mL H2O containing 2.0 g sodium dithionite, and the solvent removed under vacuum to give 16.2 g of N-(2-(2,5-dimethoxy-4-iodophenyl)ethyl)phthalimide as yellow amber solids with a mp of 133-141 deg C. This mp was improved by recrystallization from 75 mL CH3CN, yielding 12.2 g of a pale yellow solid with mp 149-151 deg C. A small sample from a large quantity of IPA gives a white product melting at 155.5-157 deg C.

A solution of 12.2 g N-(2-(2,5-dimethoxy-4-iodophenyl)ethyl)phthalimide in 150 mL hot IPA was treated with 6.0 mL of hydrazine hydrate, and the clear solution was heated on the steam bath. After a few minutes there was the generation of a white cottage cheese-like solid (1,4-dihydroxyphthalizine). The heating was continued for several additional h, the reaction mixture cooled, and the solids removed by filtration. These were washed with 2x10 mL EtOH, and the pooled filtrate and washes stripped of solvent under vacuum giving a residue which, when treated with aqueous hydrochloric acid, gave 3.43 g of voluminous white crystals. This, after recrystallization from 2 weights of H2O, filtering, washing first with IPA and then with Et2O, and air drying, gave 2.16 g 2,5-dimethoxy-4-iodophenethylamine hydrochloride (2C-I) as a white microcrystalline solid,