Convenient Route to Primary (Z)-Allyl Amines and Homologs

Abstract

A convenient two-step procedure for the synthesis of primary (Z)-allyl amines, (Z)-homoallyl amines [(Z)-but-3-enylamines], and (Z)-pent-4-enylamines using the Wittig reaction was achieved. The use of nonstabilized ylides from triphenylphosphonium salt, potassium salt, and apolar solvent produced (Z/E)-geometric isomer ratios generally greater than 1.6. The amine moiety was masked using a phtalimide group that was removed successfully in the last step of the process in two different conditions, NH₂NH₂/EtOH/rt or CH₃NH₂/EtOH/rt. However, in some cases, reduction of the C = C double bond in the deprotection with hydrazine was concomitantly observed.

Keywords:

• (Z)-Allyl amine
• (Z)-homoallyl amine
• (Z)-pent-4-enylamine

ACKNOWLEDGMENT

Financial support came from Fondo Clemente Estable and Comisión Sectorial de Investigación Cientifica-Universidad de la República (Uruguay). A. G. thanks Programa de Desarrollo de Ciencias Básicas-QUÍMCIA for a doctoral fellowship. M. B. thanks Network for Research and Training in Parasitic Diseases at the Southern Cone of Latin America-Swedish Agency for Research Cooperation with Developing Countries (RTPD-SAREC) for a scholarship.

Notes

^a Bp: boiling point at 760 mm Hg.

^b E ^N _T: empirical parameter of solvent polarity (kcal mol⁻¹).^[18]

^c The yield was determined at the same reaction time, 12 h at reflux.

^d Isolated products by chromatographic column.

^e Yield of the geometric isomers mixture.

^f Determined by ¹H NMR.

^a Isolated products by chromatographic column.

^b Yield of the geometric isomers mixture.

^c Determined by ¹H NMR.

^a Isolated products by chromatographic column.

^b Yield of the geometric isomers mixture.

^c Determined by ¹H NMR.

^d Method A.

^e Less than 2% of the double bond reduction product was isolated and characterized by ¹H NMR.

^f Method B.

^g Near to 13% of the double bond reduction product was isolated and characterized by ¹H NMR.