Intramolecular [4 + 2] Cycloadditions of Iminoacetonitriles:  A New Class of Azadienophiles for Hetero Diels−Alder Reactions

• Published in: Journal of the American Chemical Society Vol. 125; no. 17; pp. 4970 - 4971
• Main Authors: Amos, David T, Renslo, Adam R, Danheiser, Rick L
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 30.04.2003; Amer Chemical Soc
• Subjects: Acetonitriles - chemical synthesis; Acetonitriles - chemistry; Alkenes - chemistry; Aza Compounds - chemistry; Chemistry; Chemistry, Multidisciplinary; Cyclization; Exact sciences and technology; Heterocyclic Compounds - chemical synthesis; Imines - chemical synthesis; Imines - chemistry; Organic chemistry; Physical Sciences; Science & Technology; CHEMISTRY; Intramolecular reaction; Reaction path; Iminonitrile; Diels Alder addition; Thermal reaction; Experimental study; Radical scavenger; Dipolar cycloaddition
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja034629o

Iminoacetonitriles participate as reactive dienophiles in stereoselective intramolecular hetero Diels−Alder reactions which afford substituted quinolizidines. The cycloadduct with exo-oriented cyano group is obtained as the major or exclusive product of the reaction as a consequence of the α-amino nitrile anomeric effect The α-amino nitrile moieties incorporated in the cycloadducts constitute latent iminium ions, which upon exposure to mild protic or Lewis acids are unmasked, setting the stage for further useful synthetic transformations. For example, reductive decyanation with NaBH3CN excises the cyano group, while Bruylants reaction with Grignard reagents and acetylides lead to α-substituted amines. The substrates for these [4 + 2] cycloadditions are prepared from readily available alcohols via a Mitsunobu coupling reaction with the previously unknown, easily prepared reagent HN(Tf)CH2CN followed by cesium carbonate promoted elimination of trifluoromethanesulfinate.