Reakcije alena i nukleofila katalizovane paladijumovim kompleksima

U sklopu ove doktorske teze proučavane su transformacije alena u prisustvupaladijumovih kompleksa, a posebno reaktivnost π-alil-paladijumovih intermedijeragenerisanih iz alena u reakcijama sa heteroatomskim nukleofilima.Reakcije alena i aril- ili vinil-halogenida u prisustvu paladijumovih kompleksa saacetatom kao nukleofilnom vrstom omogućava direktan pristup strukturno kompleksnimalilnim acetatima. Alilni acetati predstavljaju korisnu klasu organskih jedinjenja koja se uvelikom obimu upotrebljavaju za reakcije alilnih alkilovanja katalizovanih prelaznimmetalima. Oni su, takođe, veoma značajni za dobijanje γ-nezasićenih derivata karboksilnihkiselina jer učestvuju u reakcijama 3,3-sigmatropnog premeštanja Claisen-Ireland-ovog tipa,dok hidrolizom mogu dati i sintetski veoma važne alilne alkohole.Mada su i sami alilni acetati supstrati za paladijumom katalizovane reakcije, razvijenisu uslovi koji omogućavaju sintezu ove klase jedinjenja u dobrim prinosima. Reakcijomnesimetričnih alena sa aril- ili vinil-halogenidima, nastaje π-alil-paladijumov intermedijer,koji u reakciji sa acetatnim anjonom generalno daje smešu regioizomernih acetata koji semogu razdvojiti. U nekim slučajevima, gde dominira sterni faktor, dobijen je samo jedanregioizomer vezivanjem nukleofila za sterno manje zaštićenu stranu π-alil-paladijumovogintermedijera. Regiohemijski ishod reakcije proučavan je i u intramolekulskim reakcijama,gde je pokazano da uslovi koji se uobičajeno koriste favorizuju nastajanje termodinamičkistabilnijeg proizvoda sa endocikličnom dvostrukom vezom...

The aim of this thesis was to investigate reactivity of allenes in the presence ofpalladium complexes, particularly reactivity of π-allylpalladium intermediates, generatedfrom allenes, and heteroatom nucleophiles.The reactions of allenes and aryl- or vinyl-halides in the presence of palladiumcomplexes, with acetate as nucleophilic species, provide a direct access to structurallycomplex allyl acetates. Allyl acetates represent a useful class of organic compoundsextensively used in the allylation processes catalysed by a range of transition metals. Anadditional important methodology, the Claisen–Ireland 3,3-sigmatropic rearrangement,employs allyl acetates or related esters to produce γ-unsaturated carboxylic acids and theirderivatives. They can also be a source of synthetically very useful allyl alcohols viahydrolytic processes.Although the allyl acetate itself is a substrate for palladium-catalysed reactions,conditions allowing the synthesis of this class of compounds were developed furnishing theproducts in acceptable yields. Nonsymmetrical allenes in reaction with aryl or vinyl halides,via π-allyl-palladium intermediates, generally afforded a separable mixture of regioisomericacetates. In some cases, where steric factors prevailed, a single regioisomer was obtained viathe nucleophilic attack on the π-allylpalladium intermediate from the less sterically hinderedside. The regioselectivity issue was also studied in intramolecular reactions. It was shownthat conditions usually employed were in favour of the thermodynamically more stableproduct with the endocyclic double bond...