A new synthesis of α,β-unsaturated γ- and δ-lactones via intramolecular acylation of α-sulfinyl carbanion

A new synthesis of α,β-unsaturated γ- and δ-lactones involving the intramolecular acylation of α-sulfinyl carbanion followed by pyrolysis is described.     

Radical Cyclization/ipso‐1,4‐Aryl Migration Cascade: Asymmetric Synthesis of 3,3‐Difluoro‐2‐propanoylbicyclo[3.3.0]octanes

A novel method for the asymmetric synthesis of 3,3‐difluoro‐2‐propanoylbicyclo‐[3.3.0]octanes involves an unprecedented intramolecular radical cyclization/ipso‐1,4‐aryl migration cascade.     

Fluoride-Catalyzed Condensation of 1-Phenylsulfinyl-1-(trimethylsilyl)cyclopropane with Carbonyl Compounds

1-Phenylsulfinyl-1-(trimethylsilyl)cyclopropane reacts with aldehydes in the presence of Bu₄NF to give 1-phenylsulfinyl-1-(α-hydroxyalkyl)cyclopropanes.     

Syntheses of (±)-thuriferic acid ethyl ester, its analogues and (±)-picropodophyllone

(±)-Thuriferic acid ethyl ester, its analogues as well as (±)-picropodophyllone have been prepared. The synthetic strategy is based on the utility of vicinal dianions derived from α-aroylsuccinic esters.     

Synthesis of gem-difluoromethylenated bicyclo[m.n.0]alkan-1-ols and their ring-expansion to gem-difluoromethylenated macrocyclic lactones

Fluoride-catalyzed stereoselective nucleophilic addition of PhSCF(2)SiMe(3) (1) to α-carboethoxycycloalkanones 2 followed by intramolecular radical cyclization of the resulting cis-3 adduct afforded the corresponding gem-difluoromethylenated bicyclic compounds 4, which underwent ring-expansion followed by the Baeyer-Villiger-type oxidation of the resulting macrocyclic ketone intermediates to give gem-difluoromethylenated macrocyclic lactones 5.     

The Morita?Baylis?Hillman Reaction of Chiral Highly Oxygenated Cyclopent‐2‐enones

The Morita? Baylis? Hillman (MBH) reactions of (4S,5R,7R,8R)‐ and (4R,5R,7R,8R)‐4‐hydroxy‐7,8‐dimethoxy‐7,8‐dimethyl‐6,9‐dioxaspiro[4.5]dec‐2‐en‐1‐ones ( 2 and 3 , resp.) with aldehydes using various catalysts were studied. A combination of Bu₃P/phenol in THF was found being optimum conditions giving the corresponding MBH adducts with high diastereoisomeric ratios. After separation, each stereomerically pure isomer of the MBH adducts was subjected to hydrolysis employing 1% aq. CF₃COOH (TFA) in a water bath of an ultrasonic cleaner to afford the corresponding polyhydroxylated cyclopentenones in good yields.     

Intramolecular acylation of α-sulfinyl carbanions with masked α,β-unsaturated esters: a general strategy to 5-alkylidene-2-cyclopentenones

A general method for the preparation of 5-alkylidene-2-cyclopentenones and their 2-phenylsulfanyl substituted derivatives, involving the intramolecular acylation of α-sulfinyl carbanions with cyclopentadiene-α,β-unsaturated esters as the key reaction followed by flash vacuum pyrolysis, is described. The reactions start from readily available Diels-Alder adducts, synthons of α-carbanions of α,β-unsaturated esters.     

Stereoselective synthesis of β-carboethoxy-γ-lactams via imino Mukaiyama aldol-type reaction of 1,4-bis(trimethylsilyloxy)-1,4-diethoxy-1,3-butadiene

The reaction of the (bis)trimethylsilyloxy derivative of diethyl succinate with imines in the presence of ZnCl₂ provides a general stereoselective entry to β-carboethoxy-γ-lactams.