Selectivity in organic photochemical reactions within zeolites and in the crystalline state
Description
The subject matter of this dissertation examines the possibility of performing stereoselective photoreactions in organized and confined medium such as crystalline state and faujasite zeolite Chapter one provides a brief introduction about the importance of conducting photochemical reactions within zeolites. This chapter also presents the properties of zeolites that make them as suitable reaction hosts for conducting photochemical reactions Chapter two presents the enantio- and diastereoselectivity obtained on the beta-lactam photoproducts obtained during photochemical reaction of alpha-oxoamides within zeolites by employing chiral inductor and chiral auxiliary approach. These substrates gave an insight into the factors responsible for the chiral induction within zeolites Chapter three presents the stereoselectivity obtained during photochemical inter- and intramolecular gamma-hydrogen abstraction on benzonorbornene phenyl ketone derivatives leading to formation of chirally enriched endo-cyclobutanol and reduction photoproducts within zeolites Chapter four discusses the diastereoselective photochemical gamma-hydrogen abstraction of 2-benzoyladamantane-2-carboxylic acid derivatives leading to cyclobutanols using chiral auxiliary strategy. Density functional calculations have been used to understand the role of cations in influencing the asymmetric induction process Chapter five presents the enantio- and diastereoselectivity obtained on the indan photoproduct obtained during photochemical delta-hydrogen abstraction of alpha-mesitylacetopheone systems Chapter six provides a brief introduction about the crystalline state media as an effective medium for achieving asymmetric induction during photochemical reactions Chapter seven discusses the use of covalent chiral auxiliary approach as an excellent strategy for obtaining high diastereoselectivity during gamma-hydrogen abstraction of alpha-oxoamide derivatives. This chapter also presents an example of a rare single crystal to single crystal transformation with the help of X-ray crystallography Chapter eight scrutinizes the effectiveness of covalent chiral auxiliary strategy in inducing high stereo selectivity in the crystalline state. Results of diastereoselective studies on three independent systems in the crystalline state using covalent chiral auxiliary approach are presented in this chapter Chapter nine discusses the solvent free synthesis of cyclobutanes using photolysis of diamine double salts formed by coupling trans-cinnamic acids to diamines. The photoexcitation of diamine salts undergoes a pedal-like conformational motion in order to bring the olefin bonds of cinnamate molecules parallel and allow dimerization to occur Chapter ten involves cis-trans geometric isomerization process of olefins in the crystalline state. The geometric isomerization process styrylethenes discussed in this chapter emphasizes the importance of void space around the reacting partners in the crystalline state