Scalable synthesis of (1-cyclopropyl)cyclopropylamine hydrochloride

Abstract

1-Cyclopropylcyclopropanecarboxylic acid (2), which is accessible on a large scale (900 mmol) from 1-bromo-1-cyclopropylcyclopropane (1) in 64% yield (89% on a 12.4 mmol scale), has been subjected to a Curtius degradation employing the Weinstock protocol to furnish the N-Boc-protected (1-cyclopropyl)cyclopropylamine 3 (76%). Deprotection of 3 with hydrogen chloride in diethyl ether gave the (1-cyclopropyl)cyclopropylamine hydrochloride (4·HCl) in 87% yield.

Keywords

• amines
• building blocks
• carboxylic acids
• Curtius degradation
• cyclopropanes