Potassium Hydroxide → 4-(7-Chloro-quinazolin-4-yl)-piperidine-1-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

Solid KOH (224 mg, 4 mmol) was added to a suspension of 4-(7-chloro-quinazolin-4-yl)-piperidine-1,4-dicarboxylic acid 1-tert-butyl ester 4-methyl ester (29a; 41 mg, 0.1 mmol) in a 1:1 mixture of dioxane and water (1 mL). The mixture was stirred at 100° C. for 3 h. It was then cooled to rt and concentrated in vacuo. The residue was dissolved in DCM and washed with water, brine, dried over anhydrous MgSO4, filtered and concentrated in vacuo to obtain crude 4-(7-chloro-quinazolin-4-yl)-piperidine-1-carboxylic acid tert-butyl ester (29b). This was dissolved in 2 mL of 3M HCl/MeOH was stirred at rt for 1 h and then concentrated in vacuo to obtain crude 4-(7-chloro-quinazolin-4-yl)-piperidine (29c) as a di-HCl salt. To a suspension of (29c) in anhydrous MeOH, was added DIEA (45 μL, 0.25 mmol) followed by (4-isopropoxy-phenyl)-carbamic acid 4-nitro-phenyl ester (48 mg, 0.15 mmol) and the mixture was stirred at rt for 1 h. It was then concentrated in vacuo and the residue was purified by flash column chromatography (silica gel, 1% MeOH/DCM) to obtain 5 mg (12% overall yield from 29a) of pure 4-(7-chloro-quinazolin-4-yl)-piperidine-1-carboxylic acid (4-isopropoxy-phenyl)-amide. 1H-NMR (300 MHz, CDCl3): δ 9.25 (s, 1H), 8.15-8.06 (m, 2H), 7.62 (d, 1H), 7.23 (d, 2H), 6.85 (d, 2H), 6.30 (s, 1H), 4.49 (m, 1H), 4.26 (m, 2H), 3.70 (m, 1H), 3.15 (m, 2H), 2.23-2.05 (m, 2H), 2.05-1.92 (m, 2H), 1.32 (d, 6H). LC/MS (ESI): calcd mass 424.2, found 425.4 (MH)+.

Provenance & Evidence