8 documents found, page 1 of 1
A3-Coupling Reaction as a Strategy Towards the Synthesis of Alkaloids
Carmona,Rafaela C.; Wendler,Edison P.; Sakae,George H.; Comasseto,João V.; Santos,Alcindo A. DosA number of aldehydes, alkynols and benzylamines were submitted to A3-coupling reaction, under CuCl catalysis, giving strategically functionalized hydroxy-propargylamines. The procedure allows the use of alkyl as well as aryl aldehydes. Representative substrates were converted into fiveand six-membered cyclic alkaloids by sequential one-pot N-debenzylation/triple bond reduction promoted by Pd, followed by a Mit...
A concise enantioselective synthesis of (+)-endo-brevicomin accomplished by a t...
Ferrarini,Renan S.; Princival,Jefferson L.; Comasseto,João V.; Dos Santos,Alcindo A.A homoenolate generated by tellurium/lithium exchange reaction was employed in a straightforward enantioselective synthesis of (+)-endo-brevicomin in 70% yield and 84.4% e.e.
Computer-aided prediction of 125Te and 13C NMR chemical shifts of diorgano tell...
Emerenciano,Vicente P.; Diego,Dennis G.; Ferreira,Marcelo J. P.; Scotti,Marcus T.; Rodrigues,Gilberto V.; Comasseto,João V.This work describes a method to predict the 125Te and 13C NMR chemical shifts of diorgano tellurides based in a three-dimensional approach. For that, a collection of 150 compounds were selected from the literature and had their geometry optimized using the PM3 semi-empirical method. From this data, the structures were coded by the FOCOS program which described the chemical environment for each atom present in t...
beta-butyltellanyl carbonyl compounds: a useful source of masked metal homoenol...
Santos,Alcindo A. dos; Comasseto,João V.Secondary higher order cyanocuprates and lithium homoenolates, were efficiently generated from beta-butyltellanylketals and reacted with benzaldehyde and 2-cyclohexen-1-one.
Vinylic tellurides as precursors in a stereoselective and convergent route to Z...
Araujo,Marcelo A. de; Raminelli,Cristiano; Comasseto,João V.Vinylic tellurides of Z configuration are transformed into higher order Z-vinyl cyanocuprates by transmetallation with higher order lithium dimethyl- or n-butyl(thienyl)cyanocuprates. Reaction of the obtained Z-vinyl cyanocuprates with zinc chloride gives presumably mixed zinc-copper species which react with bromoalkynes leading to enynes and enediynes with retention of the Z double bond configuration.
A short and efficient enantioselective synthesis of (+) and (-)-(Z)-7,15-hexade...
Clososki,Giuliano C.; Ricci,Luis C.; Costa,Carlos E.; Comasseto,João V.The (R) and the (S) enantiomers of the Z-7,15-hexadecadien-4-olide (4), the sex pheromone of Heptophylla picea, were synthesized. A known lipase-catalysed enantiolactonization in the key step afforded a common precursor for both enantiomers of the pheromone in 92% e.e.
Hydrotelluration of alkynes: a unique route to Z-vinyl organometallics
Vieira,Maurício L.; Zinn,Fabiano K.; Comasseto,João V.The hydrotelluration reaction of alkynes is reviewed. The transformation of vinylic tellurides into reactive vinyl organometallics and the coupling reactions of vinylic tellurides with alkynes and organometallics are presented.
The Influence of the Substrate Structure in the Tellurocyclofunctionalization R...
Moraes,Denilson N.; Santos,Rute A.; Comasseto,João V.<FONT FACE=Symbol>g,d</FONT>-Unsaturated carboxylic acids containing monosubstituted double bonds react with aryltellurium trichlorides to give the expected tellurolactone. Reaction of the corresponding benzyl esters gives the addition product of the aryltellurium trichlorides to the double bond. <FONT FACE=Symbol>g,d</FONT>-Unsaturated carboxylic acids containing 1,1-disubstituted double bonds lead to a mixtur...