Palladium-Catalyzed Stereoselective Allylaminocyclization and 1,3-Butadien-2-ylaminocyclization of Allenyl Tosylcarbamates
摘要:
Palladium [PdCl2(PhCN)(2) or Pd-2(dba)(3) . CHCl3 (dba = dibenzylideneacetone)], in the presence of a base (Et(3)N 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(PPh(3))(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(PPh(3))(4) and PdCl2(PhCN)(2) catalyze a formal dimerization of 1 to provide C-4-triene-substituted 2-oxazolidinones 4 in moderate to good yields.
Silver(I)-Catalyzed Aminocyclization of 2,3-Butadienyl and 3,4-Pentadienyl Carbamates: An Efficient and Stereoselective Synthesis of 4-Vinyl-2-oxazolidinones and 4-Vinyltetrahydro-2H-1,3-oxazin-2-ones
Palladium [PdCl2(PhCN)2 or Pd2(dba)3.CHCl3] catalyzes the reaction of O-(2,3-butadienyl) N-tosylcarbamates 1 with allylic chlorides to selectively provide trans-4,5-disubstituted oxazolidin-2-ones 2 in good yields. Under similar conditions, Pd(PPh3)4 catalyzes an N-allylation of 1 to give 3, and chloro-pi-allylpalladium(II) dimer promotes a dimerization of 1g and gives 4 as a major product together with 2.
Pd2+-catalyzed oxidative aminocarbonylation of O-2,3-butadienyl and O-3,4-pentadienyl N-tosylcarbamates
Pd2+-catalyzed aminocarbonylation of O-2,3-butadienyl 1 and O-3,4-pentadienyl carbamates 5 stereoselectively provides 4-(1-methoxycarbonylvinyl)-1,3-oxazolidin-2-ones 2 and 4-(1-methyoxycarbonylvinyl)-1,3-oxazin-2-ones 6, respectively, in high yields.