electrophiles including alkyl halides, carbonyl compounds, and sodium iodoacetate. A convenient synthetic method for 4-alkyl- and 5-alkyl-2(5H)-furanones has been developed by using these dianions. A new synthetic approach to trans-3,4-bis(3-hydroxybenzyl)dihydro-2(3H)-furanone, the first lignan found in humans, via a facile reduction of 2(5H)-furanone with Mg-methanol is also decribed.
Treatment of N-phenyl-3-(phenylsulfonyl)propanamide with 2 equiv. of butyllithium at −78 °C afforded the dianion. Aldehydes and ketones upon treatment with the dianion provided stable γ-hydroxy amides, which were converted in good yields to 5-alkyl-2(5H)-furanones. Optically active (R)- and (S)-5-octyl-2(5H)-furanones, and (R)- and (S)-5-tridecyl-2 (5H)-furanones were prepared from aldehydes and the dianions, derived from chiral N-monosubstituted-3-(phenylsulfonyl)propanamides.
1-Benzyloxy-3-(p-tolylsulfonyl)propene as an acrolein β-anion equivalent. Synthesis of 4-substituted 2-butenolides
作者:Donald Craig、Christopher J. Etheridge、Alison M. Smith
DOI:10.1016/s0040-4039(00)60211-3
日期:1992.11
Lithiation of 1-benzyloxy-3-(p-tolylsulfonyl)propene 6 and reaction with aldehydes give alcohols 7. Sequential hydrolysis-cyclization, oxidation and DBU-mediated elimination of dine elements of p-TolSO2H gives 4-substituted 2-butenolides 10 in good overall yield.
Preparation and reactivity of functionalized alkenyl-zinc, -copper, and -chromium organometallics
作者:Paul Knochel、C. Janakiram Rao
DOI:10.1016/s0040-4020(01)80504-4
日期:1993.1
Beta-halogeno-alpha,beta-unsaturated carbonyl derivatives were converted to the corresponding zinc organometallics 2a under mild conditions in THF (Zn dust, 25-45-degrees-C, 1-4h). These functionalized alkenylzinc iodides react with a variety of alkenyl and aromatic iodides affording the desired coupling products in 40-97% yield. The addition of a THF solution of CuCN.2LiCl to 2a affords the corresponding organocopper derivatives 2b which react with electrophiles, such as alkynyl and allylic halides, nitro olefins, enones, and chlorotrimethylstannane providing polyfunctional unsaturated carbonyl compounds in 71-95% yield. The insertion of chromium (II) chloride to beta-iodo and to some beta-(p-tosyl)enones in DMF furnishes new functionalized chromium (III) organometallics 2c which react with aldehydes providing gamma-hydroxy unsaturated carbonyl derivatives in 40-91% yield. The synthetic scope and the limitations of this methodology are discussed.
Trans-Selective Conversions of γ-Hydroxy-α,β-Alkynoic Esters to γ-Hydroxy-α,β-Alkenoic Esters
作者:Christopher T. Meta、Kazunori Koide
DOI:10.1021/ol0495366
日期:2004.5.1
gamma-Hydroxy-alpha,beta-acetylenic esters are used as precursors to prepare gamma-hydroxy-alpha,beta-alkenoic esters by means of trans-selective additions of two hydrogen atoms or one hydrogen atom and one iodine atom across the triple bonds. These methods allow for the preparation of beta-substituted and alpha,beta-disubstituted alkenoic esters in highly stereoselective manners.