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V magistrskem delu sem raziskoval Diels–Alderjevo reakcijo med substituiranimi 2H-piran-2-oni in maleinanhidridom. Izhodne 2H-piran-2-one sem pripravil z enoločno sintezo, pri čemer so nastali različno substituirani 3-benzoilamino-2H-piran-2-oni. Slednji pri reakcijah z maleinanhidridom pod termičnimi pogoji običajno tvorijo enega izmed dveh možnih produktov: biciklični dvojni adukt (derivatiziran biciklo[2.2.2]okten) ali termodinamsko stabilnejši aromatski produkt (derivat izobenzofurana). Z optimizacijo reakcijskih pogojev sem poskušal pripraviti ter izolirati obe vrsti produktov. Izkazalo se je, da je reaktivnost 2H-piran-2-onov, ki vsebujejo elektron donorske substituente, pri reakciji z maleinanhidridom večja kot je reaktivnost 2H-piran-2-onov z elektron privlačnimi substituenti v obeh primerih nastanejo biciklični dvojni adukti z dobrimi izkoristki, v drugem primeru pa tudi aromatizirani izobenzofuranski produkti. 2H-piran-2-oni z elektron donorskimi substituenti torej preferenčno tvorijo biciklične adukte, ki se v večini primerov tudi po daljšem reakcijskem času in višji reakcijski temperaturi slabo pretvarjajo v aromatske. In the present work I investigated the Diels–Alder reaction between substituted 2H-pyran-2-ones and maleic anhydride. The starting 2H-pyran-2-ones were synthesised by “one pot” synthesis, resulting in various substituted 3-benzoylamino-2H-pyran-2-ones. The latter when reacted with maleic anhydride under thermal conditions usually form one of the two possible products: a bicyclic double adduct (derivatized bicyclo[2.2.2] octene) or a thermodynamically more stable aromatic product (isobenzofuran derivative). By optimizing the reaction conditions, I tried to prepare and isolate both types of products. The reactivity of 2H-pyran-2-ones with electron donor substituents in the reaction with maleic anhydride has been shown to be greater than the reactivity of 2H-pyran-2-ones with electron-withdrawing substituents, resulting in the formation of bicyclic double adducts (with good yields) in the former case and aromatic isobenzofuran products in the latter. In contrast, 2H-pyran-2-ones with electron donor substituents preferentially form a bicyclic adduct, which in most cases is poorly converted to aromatic even after a long reaction time and higher reaction temperature. |
