Cyclization of Trichloroacetimidates by Olefin Aminopalladation β-Heteroatom Elimination

• Published in: European Journal of Organic Chemistry Vol. 2009; no. 36; pp. 6407 - 6412
• Main Authors: Maleckis, Ansis, Jaunzeme, Ieva, Jirgensons, Aigars
• Format: Book Review Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.12.2009; WILEY‐VCH Verlag; Wiley; Wiley-VCH
• Subjects: Amination; Chemistry; Chemistry, Organic; Chirality; Elimination; Exact sciences and technology; Heterocycles; Heterocyclic compounds; Heterocyclic compounds with n hetero atom and also o and/or s, se, te hetero atoms; Kinetics and mechanisms; Organic chemistry; Palladium; Physical Sciences; Preparations and properties; Reactivity and mechanisms; Science & Technology; Heterocycles; AEROBIC OXIDATIVE AMINATION; ENANTIOSELECTIVE SYNTHESIS; Elimination; ASYMMETRIC INTRAMOLECULAR AMINOPALLADATION; Palladium; HYDROAMINATION; UNACTIVATED ALKENES; Chirality; AMINO-ACIDS; CONSTRUCTION; DIAMINATION; Animation; N BOND FORMATION; Molecular orbital; Palladium II; Palladium complex; Chiral compound; Selectivity; Allylic compound; Stereoselectivity; Imide; Amination; Reaction mechanism; Platinoid; Heterocyclic compound; Oxygen nitrogen heterocycle; Anti stereoisomer; Catalytic reaction; Overman rearrangement; Transition metal; Oxazine derivatives; Olefin; Cyclization; Ethylenic compound
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.200900917

The cyclization of δ‐acetoxy‐O‐allyl‐ and ϵ‐acetoxy‐O‐homoallyl‐trichloroacetimidates to 4‐vinyloxazolines and a 4‐vinyldihydrooxazine has been efficiently achieved by olefin aminopalladation–β‐heteroatom elimination. (Z)‐Allylic imidates bearing a secondary δ‐acetoxy group underwent PdII‐catalysed cyclization to give the E isomers of 4‐vinyloxazolines selectively and gave no Overman rearrangement products. Using a chiral substrate, it has been demonstrated that cyclization to 4‐vinyloxazolines occurs with high chirality transfer. Stereoselective E isomer formation and chirality transfer provided a basis from which to discuss the possible reaction mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) PdII‐catalysed cyclization of O‐allylic and O‐homoallylic trichloroacetimidates provides 4‐vinyloxazolines and a 4‐vinyldihydrooxazine, respectively. (Z)‐Allylic imidates with a secondary δ‐acetoxy groupgive (E)‐4‐vinyloxazolines selectively and with high chirality transfer. The mechanism of the reaction is discussed based on the observed stereoselectivity.