1-N-Boc-4-Piperidinecarboxylic acid methyl ester → 4-(7-Fluoro-quinazolin-4-yl)-piperidine-1,4-dicarboxylic acid 1-tert-butyl ester 4-methyl ester

Participants

Reaction Steps

A mixture of 4-chloro-7-fluoro-quinazoline (2.87 g, 15.4 mmol) (WO 9609294 A1) and piperidine-1,4-dicarboxylic acid 1-tert-butyl ester 4-methyl ester (4.15 g, 17.1 mmol), as prepared in Example 1b, was placed in a −78° C. bath for 5 min under argon before adding a 1.08 M LiHMDS/THF solution (17.8 mL, 19.2 mmol) rapidly by syringe along the sides of the flask (to allow cooling and dispersion of the hindered base before reaction with the ester). Following completion of LiHMDS/THF addition, the reaction was manually swirled in the −78° C. bath for 2-3 min before removing the cold bath and allowing the mixture to stir with gradual warming to rt. After 2.5 h stirring at rt, the dark brown homogeneous solution was quenched with 1.0 M NaH2PO4 (38 mL) and extracted with DCM (1×150 mL and 1×25 mL). The organic layers were combined, dried (Na2SO4), and concentrated under reduced pressure, and subject to high vacuum at 90° C. with toluene chasers (3×10 mL) to provide the crude title compound as an opaque thick yellow oil that was used in the next step without further purification (6.83 g, “114%” crude yield). 1H-NMR (300 MHz, CDCl3) δ 9.26 (s, 1H), 8.11 (dd, 1H), 7.70 (dd, 1H), 7.36 (ddd, 1H), 3.74-3.64 (m, 2H), 3.62-3.51 (m, 2H), 3.61 (s, 3H), 2.47-2.38 (br m, 4H), 1.46 (s, 9H). LC/MS (ESI): calcd mass 389.2, found 390.1 (MH)+.

Provenance & Evidence