1H-Indazole-1-carboxylic acid, 3-iodo-5-(phenylMethoxy)-, 1,1-diMethylethyl ester synthesis

Yield:-

Reaction Conditions:

with dmap;triethylamine in dichloromethane at 20;

Steps:

IV

Stage IV: Procedure B Preparation of 5-benzyloxy-3-iodoindazole-1-carboxylic Acid Tert-butyl Ester 1.70 g of 4-dimethylaminopyridine are added to a solution of 19.54 g of 5-benzyloxy-3-iodo-1H-indazole, 36.50 g of di-tert-butyl dicarbonate and 23.30 ml of triethylamine in 550 ml of dichloromethane. A substantial amount of gas is seen to be given off. The solution is stirred overnight at ambient temperature. The organic phase is washed with 2*500 ml of distilled water, dried over magnesium sulfate, filtered, and concentrated under reduced pressure in a rotary evaporator. The crude solid is taken up in acetonitrile. The solid is filtered off, and rinsed with acetonitrile and ethyl ether. 19.43 g of 5-benzyloxy-3-iodoindazole-1-carboxylic acid tert-butyl ester are collected. The filtrate is purified by flash chromatography (silica 70-200 μm), eluent: 3/97 ethyl acetate/cyclohexane. 3.05 g of 5-benzyloxy-3-iodoindazole-1-carboxylic acid tert-butyl ester are collected.

References:

US2005/137171,2005,A1 Location in patent:Page/Page column 11