4-Chlorobenzenesulfonyl chloride → N-(N-(N-(N-(4-chlorobenzenesulfonyl)-L-alanyl)-L-alanyl)-L-prolyl)-L-valine [11beta,21-dihydroxy-3,20-dioxo-6alpha-methyl-17-propionyloxy-pregna-1,4-dien-21-yl] ester

Participants

Reaction Steps

100 mg (0.11 mmol) of H-Ala-Ala-Pro-Val-O-MPP x TFA (Example 3) and 300 μl (1.71 mmol) of diisopropylethylamine are dissolved in 5 ml of tetrahydrofuran, mixed with 238 mg (1.13 mmol) of 4-chlorobenzenesulfonic acid chloride and stirred for 23 hours at room temperature. The residue that remains after removal of the solvent i.vac. is chromatographed. Gradient chromatography on 25 g of silica gel 60 (hexane/acetone 2:1→1:2) yields 75 mg (70%) of N-(N-(N-(N-(4-chlorobenzenesulfonyl)-L-alanyl)-L-alanyl)-L -prolyl)-L-valine [11β,21-dihydroxy-3,20-dioxo-6α-methyl-17-propionyloxy-pregna-1,4-dien-21-yl] ester, and, after recrystallization from dichloromethane/diisopropyl ether, 47 mg (44%) of crystalline product.

Provenance & Evidence