138212-37-0Relevant articles and documents
Palladium-Catalyzed Stereoselective Allylaminocyclization and 1,3-Butadien-2-ylaminocyclization of Allenyl Tosylcarbamates
Kimura, Masanari,Tanaka, Shuji,Tamaru, Yoshinao
, p. 3764 - 3772 (1995)
Palladium , in the presence of a base (Et3N or K2CO3) in THF at room temperature, catalyzes an allylaminocyclization of 2,3-butadienyl tosylcarbamates 1 with allylic chlorides to selectively provide trans-4,5-disubstituted 2-oxazolidinones 2 in good yields.Under similar conditions, Pd(PPh3)4 catalyzes an N-allylation of 1 to give 3.A limited number of 3,4-pentadienyl tosylcarbamates 5 undergo the allylaminocyclization to provide tetrahydro-1,3-oxazin-2-ones 6.In the absence of an allylic chloride, Pd(PPh3)4 and PdCl2(PhCN)2 catalyze a formal dimerization of 1 to provide C4-triene-substituted 2-oxazolidinones 4 in moderate to good yields.
Dormant versus evolving aminopalladated intermediates: Toward a unified mechanistic scenario in PdII-catalyzed aminations
Rajabi, Jamshid,Lorion, Melanie M.,Ly, Vu Linh,Liron, Frederic,Oble, Julie,Prestat, Guillaume,Poli, Giovanni
supporting information, p. 1539 - 1546 (2014/03/21)
PdII-catalyzed alkene aminopalladation and allylic Ci￡H activation are two competing reaction sequences sharing the same reaction conditions. This study aimed at understanding the factors that bias one or the other path in the intramolecular oxidative cyclization of two types of N-tosyl amidoalkenes. The results obtained are in accord with the initial generation of a high-energy cyclic (5- or 6-membered) aminopalladated intermediate. However, this latter species can evolve only if the following specific conditions are met: the availability of distocyclic β-H elimination pathway, the presence of a strong terminal oxidant, or the availability of a carbopalladation pathway. Conversely, the cyclic alkylpalladium complex is only a latent species in equilibrium with the initial substrate and cannot evolve. Such a reactivity hurdle leaves the way open for alternative reactivities such as allylic Ci￡H activation of the olefinic substrate to generate a η3-allyl complex followed by its interception by the nitrogen nucleophile, [3,3]-sigmatropic rearrangement, or decomposition. This study proposes a unifying mechanistic picture that connects these competing mechanisms. Asleep or awake? Unsaturated N nucleophiles react through two competing pathways under PdII catalysis: Ci￡H allylic activation and aminopalladation. New data are in accord with the initial generation of a high-energy cyclic aminopalladated intermediate (API) that can either evolve along different pathways such as β-H elimination, oxidation, or carbopalladation, or lay dormant, the latter leading to alternative types of reactivity, such as allylic Ci￡H activation or [3,3]-sigmatropic rearrangement, gaining the upper hand (see scheme; Ts=p-toluenesulfonyl). Copyright
Palladium(II)-catalyzed oxidative cyclization of allylic tosylcarbamates: Scope, derivatization, and mechanistic aspects
Joosten, Antoine,Persson, Andreas K. ?.,Millet, Renaud,Johnson, Magnus T.,B?ckvall, Jan-E.
, p. 15151 - 15157 (2013/01/15)
A highly selective oxidative palladium(II)-catalyzed (Wacker-type) cyclization of readily available allylic tosylcarbamates is reported. This operationally simple catalytic reaction furnishes tosyl-protected vinyl-oxazolidinones, common precursors to syn-1,2-amino alcohols, in high yield and excellent diasteroselectivity (>20:1). It is demonstrated that both stoichiometric amounts of benzoquinone (BQ) as well as aerobic reoxidation (molecular oxygen) is suitable for this transformation. The title reaction is shown to proceed through overall trans-amidopalladation of the olefin followed by β-hydride elimination. This process is scalable and the products are suitable for a range of subsequent transformations such as: kinetic resolution (KR) and oxidative Heck-, Wacker-, and metathesis reactions.
