82721-81-1Relevant articles and documents
Highly stereoselective three-component reactions of phenylselenomagnesium bromide, acetylenic sulfones, and saturated aldehydes/ketones or α,β-unsaturated enals or enones
Huang, Xian,Xie, Meihua
, p. 8895 - 8900 (2007/10/03)
β-Phenylseleno-α-tolylsulfonyl-substituted alkenes were synthesized via the three-component conjugate-nucleophilic addition of acetylenic sulfones, phenylselenomagnesium bromide, and carbonyl compounds, such as aldehydes, aliphatic ketones, or α-unsaturated enals or enones. The reaction is highly regio- and stereoselective with moderate to good yields. Functionalized allylic alcohols were obtained in the case of aldehydes and aliphatic ketones. In the case of α,β-unsaturated enones, functionalized allylic alcohols or functionalized γ,δ-unsaturated ketones were obtained, depending on the structures of the ketones.
A convenient new route to piperidines, pyrrolizidines, indolizidines, and quinolizidines by cyclization of acetylenic sulfones with β- and γ-chloroamines. Enantioselective total synthesis of indolizidines (-)-167B, (-)-209D, (-)-209B, and (-)-207A
Back, Thomas G.,Nakajima, Katsumasa
, p. 4543 - 4552 (2007/10/03)
The methyl esters of (L)-phenylalanine and (L)-methionine underwent conjugate additions via their free amino groups to 1-(p-toluenesulfonyl)hexyne, followed by intramolecular acylation of the corresponding enamide anions and tautomerization to afford 2-benzyl-5-n-butyl-3-hydroxy-4-(p-toluenesulfonyl)pyrrole and 5-n-butyl-3-hydroxy-2-(2-methylthioethyl)-4-(p-toluenesulfonyl)pyrrole, respectively. The conjugate additions of a series of acyclic and cyclic secondary β- and γ-chloroamines to acetylenic sulfones proceeded similarly under mild conditions. The resulting adducts were deprotonated with LDA in THF at -78 °C, and the resulting sulfone-stabilized carbanions underwent intramolecular alkylation to afford cyclic enamine sulfones. Thus, acyclic γ-chloroalkylbenzylamines afforded the corresponding 2- or 2,6-disubstituted piperidines, while 2-(chloromethyl)-pyrrolidines, 2-(2-chloroethyl)pyrrolidines, 2-(chloromethyl)piperidines, and 2-(2-chloroethyl)-piperidines produced the corresponding 3-substituted pyrrolizidines, 5- or 3-substituted indolizidines, and 4-substituted quinolizidines, respectively. 8-Methyl-5-substituted indolizidines were also prepared from the appropriate methyl-substituted chloroamine precursor. Enantioselective syntheses were achieved by employing chiral chloroamines derived from amino acids or other enantiopure precursors. Further transformations of several of the products provided concise syntheses of four dendrobatid alkaloids. Thus, reduction of (8aS)-5-n-propyl-6-(p-toluenesulfonyl)-Δ-indolizidine with sodium cyanoborohydride in trifluoroacetic acid, followed by reductive desulfonylation, afforded (-)-indolizidine 167B. The corresponding 5-n-hexyl derivative similarly produced (-)-indolizidine 209D, while (-)-(8R,8aS)-8-methyl-5-n-pentyl-6-(p-toluenesulfonyl)-Δ5,6-indolizidine furnished (-)-indolizidine 209B. Finally, the similar reduction and debenzylation of (-)-(8R,8aS)-5-(2-benzyloxyethyl)-8-methyl-6-(p-toluenesulfonyl)-Δ-indolizid ine produced the corresponding 5-hydroxyethyl indolizidine. This was subjected to chlorination of the alcohol group with thionyl chloride and substitution with a higher order allyl cuprate reagent to afford (-)-indolizidine 207A.
Synthesis of (6S,7S,9R,10R)-6,9-epoxynonadec-18-ene-7,10-diol, a marine epoxy lipid isolated from the brown alga, Notheia anomala, by an oxiranyl anion strategy
Mori, Yuji,Sawada, Tomoko,Furukawa, Hiroshi
, p. 731 - 734 (2007/10/03)
The stereocontrolled synthesis of (6S,7S,9R,10R)-6,9-epoxynonadec-18- ene-7,10-diol, isolated from the brown alga, Notheia anomala, has been achieved. The key 2,3,5-trisubstituted tetrahydrofuran ring was constructed by alkylation of the sulfonyl-stabilized oxiranly anion followed by 5-endo cyclization.
Addition of Phenyl Areneselenosulphonates to Acetylenes: a Route to Acetylenic Sulphones
Miura, Takashi,Kobayashi, Michio
, p. 438 - 439 (2007/10/02)
Treatment of phenyl areneselenosulphonates (1) with terminal acetylenes resulted in the formation of β-(phenylseleno)vinyl sulphones (2), which on treatment with excess of hydrogen peroxide in tetrahydrofuran at room temperature gave acetylenic sulphones
