Palladium Catalyzed Multicomponent Cascade Reactions

This Thesis is divided into three parts: Introduction (Chapter 1), Result and Discussion (Chapter 2) and Experimental (Chapter 3). The Introduction (Chapter 1) provides a review of the recent literature relating to the 1,3dipolar cycloaddition reactions. It· covers nitrones, azomethine ylides and azomethine imines. The Result and Discussion. section (Chapter 2) deals with the author's work which is . concerned with developing four novel multicomponent cascade reactions. These are (i) a 3- component cascade involving bifunctional aryl halide! Michael acceptors, allene and arriine or sulphonamide nucleophiles (ii) a 3-component cascade involving bifunctional arylhalide! Michael acceptors, carbon monoxide and primary ~nes (iii) a 4-component cascade involving a bifunctional aryliodide! aldehyde, hydrazines, allene and· a dipolarophile and (iv) a 3-component cascade involving 2-bromomethyl iodobenzene, carbon monoxide and / ' hydrazines. { Cascade (i) and (ii) employ a common bifunctional Michael acceptor! arylhalide and a series of these were prepared all of which had an a, .p- unsaturated amide as the Michael acceptor. In·niost caSe these contained a chiral amide function while enabled the author to study chiral induction and diastereomer product ratios. In series (i) product yields ranged from 54-75% but there was essentially no chiral induction (dr's 1:1-1:1.6). Series (ii) gave a range of interesting isoindolones in 61-78% yield but again there was no significant chiral induction (dr 1:1-1:1.7). In both series we concluded the chiral amide centre is too distant from the site of the newly created chiral centre to have a controlling influence. Series (iii), the 4-component cascade proceeded regia-and stereoselectively in 55-72% yield. The IH NMR spectra of the pyrazolidine products showed line broadening due to N-Ione pair inversion processes which was confirmed by variable temperature IH NMR studies. An approximate inversion barrier of 12-15 Kcals.morl wa~ estimated. The final series, series (iv), was only briefly studi~d with two examples completed in 61-64% yield. .The thesis concludes (Chapter 3) with full experimental details' of all new compounds together with their appropriate physical, spectroscopic and analytical data.EThOS - Electronic Theses Online ServiceGBUnited Kingdo