Further investigations into the novel photo-NOCAS reaction-changing the vinyl ether and nucleophile

Abstract

The study carried out here further expanded on the previously reported novel photo NOCAS (Nucleophile Olefin Combination with Aromatic Substitution) reaction incorporating ethyl vinyl ether. The reaction is a novel reaction pathway which incorporates four reactant molecules into a final product through a series of intermediate steps, requiring less solvent wastage as well as forming a compound which is not easily synthesised through normal pathways. The purpose of the study was to investigate the effects of changing the vinyl ether and the nucleophile so as to further the scope of the reaction. The first part of the study involved changing the vinyl ether to 1,1-dimethoxyethene. No reaction involving this ether was observed. It is thought that polymerisation and/or the difficulty of formation of a key intermediate was responsible for this negative result. The second part involved changing the nucleophile from methanol to ethanol while still using ethyl vinyl ether as the olefin. The reasons for using ethanol were twofold. No photo NOCAS type products incorporating ethanol have been previously reported to date. Furthermore, incorporating ethanol into the product was expected to give simpler 1H NMR spectrum than that obtained in previous studies, since the expected main product would not possess a chiral centre. The product obtained from the reaction was 4-(5,5-diethoxy-2,3,3 trimethylpentan-2-yl)cyanobenzene, which was characterised fully by spectroscopic means. Further proof of structure was provided by means of hydrolysis of this product to yield the aldehyde 4-(4-cyanophenyl)-3,3,4-trimethylpentan-1-al. A second product was also isolated from the reaction. However full characterization was not possible and only a partial tentative structure has been proposed. Finally, the normal photo-NOCAS reaction (i.e. in absence of a vinyl ether) was carried out with ethanol. The product obtained from this reaction was 3-( 4-cyanophenyl)-2-ethoxy 2,3-dimethylbutane.