Enantioselective construction of highly functionalized bicyclo[4.3.0] system through Diels-Alder cycloaddition
摘要:
The Diels-Alder reaction of chiral 2-alkylsulfinyl-1-nitroalkene 4 with Danishefsky`s diene afforded adducts 9a and 10a in good chemical yield with a high enantiomeric excess, while diastereomeric nitroalkene 5 gave 9b and 10b, enantiomeric to 9a and 10a, respectively. The synthesis of the chiral dienophiles and mechanism of the chiral induction in the cycloaddition are discussed.
Several γ, δ-unsaturated sulfinyl compounds were prepared and their reactions with p-toluenesulfonic acid were examined. Conformationally rigid γ, δ-unsaturated sulfinyl compounds such as endo-(alkylsulfinyl)norbornene or 1-(alkylsulfinyl)-2-isopropenylbenzene derivatives afforded 1, 3-oxathianes through intramolecular Pummerer rearrangement.
The reaction of β-nitro-α,β-unsaturated sulfoxide 7 with δ-lactam enolates 11 – 15 afforded 20 – 24, respectively, in good chemical yields with high enantiomeric excesses.
Several beta-seleno-alpha, beta-unsaturated nitroalkenes were prepared via an addition-elimination process using the corresponding sulfinyl compounds and phenyl or methyl selenol.
Enantioselective construction of highly functionalized bicyclo[4.3.0] system through Diels-Alder cycloaddition
The Diels-Alder reaction of chiral 2-alkylsulfinyl-1-nitroalkene 4 with Danishefsky`s diene afforded adducts 9a and 10a in good chemical yield with a high enantiomeric excess, while diastereomeric nitroalkene 5 gave 9b and 10b, enantiomeric to 9a and 10a, respectively. The synthesis of the chiral dienophiles and mechanism of the chiral induction in the cycloaddition are discussed.