Abstract
This thesis aims at the studies on the novel rearrangement of 2-hydroxybenzophenone on reaction with Corey-Chaykovsky reagent. The first part is concerned with the effects of substituents on 2-hydroxybenzophenone and the second part describes the plausible mechanism for the observed products. When n-butyllithium (n-BuLi) was used as base in tetrahydrofuran (THF) to generate Corey-Chaykovsky reagent, it was found that the reagent had totally different reactivity towards the substrate in comparison to Corey-Chaykovsky reagent prepared using sodium hydride (NaH) as base in dimethylsulfide (DMSO). Initially, various substituted 2-hydroxybenzophenones were prepared from Grignard reactions of benzaldehyde derivatives followed by sequential oxidation and deprotection. These substrates were next subjected to Corey-Chaykovsky reaction to afford three kinds of products, two of which are one-carbon homologated products with different regioselectivity called the rearranged product Ⅰ andⅡ, and the third being cyclized product. The rearranged products Ⅰ were obtained for 2-hydroxybenzophenones with electron-donating substitutions or weakly electron-withdrawing substitutions on the aryl ring and were accompanied by the cyclized products. A strongly electron-withdrawing substituent like nitro group at the position 4’ led to the rearranged productⅡ. Four pathways are suggested for furnishing the observed products in which two are used to interpret formation of the cyclized compounds. The epoxide compound (122) is considered to be the intermediate in these two paths. To confirm the proposed mechanisms, protected epoxide compounds were obtained by epoxidation of t-butyldimethylsilyl chloride (TBDMSCl) and p-methoxybenzyl bromide (PMBBr) protected 2-hydroxybenzophenone. These compounds were subjected to Corey-Chaykovsky reaction condition to generate the cyclized products. Consequently, it is now proved that the epoxide intermediate exits in the reaction and the pathway might be correct for the formation of the cyclized products.