Chiral nitrone reagents for cycloaddition reactions

Abstract

The preparation and cycloaddition reactions of new imidazoline nitrones are described. The imidazo[1,2‐b]isoxazole alkene cycloadducts are formed via an exo approach. An example has been tranformed into a pyrrolo[1,2‐a]imidazole as a prelude to a new pyrrolidine synthesis.

Asymmetric Reactions

“…are popular targets and have demonstrated their reactivity toward various dipolarophiles, (e.g., styrene, Scheme 1.80) (420)(421)(422)(423)(424)(425)(426)(427)(428)(429)(430)(431). However, only one group reports the use of a 2-imidazoline nitrone (432)(433)(434), which has demonstrated complete diastereofacial selectivity in its reactions with electron-…”

1,3-Dipolar cycloaddition reaction of 4,5-dihydro-1H-imidazole 3-oxides with alkynes

“…Examples of reaction of derivatives of 4,5-dihydro-1H-imidazole 3-oxide with alkenes are described in literature [20,21]. Our efforts to obtain cycloadducts by the reaction of 2a, 3a,b, 6a,b with alkenes in different conditions were failed.…”

“…The first attempts of using the derivative of the 4,5-dihydro-1H-imidazole 3-oxide in 1,3-dipolar cycloaddition reactions have been recently made (Scheme 1) [19][20][21].…”