Studies On The Selective Bond Cleavage Of Two Kinds Of Benzotriazole Derivatives And Its Application In Organic Synthesis

Benzotriazole (BtH), an ideal auxiliary reagent in organic synthesis, is low-cost, non-toxic and chemically stable. Benzotriazole could be easily introduced into a variety of compounds through the addition and condensation reactions so that a variety of benzotriazole derivatives can be prepared.The. derivatives are usually crystalline solids and easy to purify. It bears good leaving ability so it can be removed readily by suitable means. The dissertation investigated the reactions involving the selective bond cleavage of two kinds of benzotriazlole derivatives, namely, N-(a-benzotriazol-1-ylalkyl)-methylcarbamate andβ-benzotriazolyl carbonyl compounds. The dissertation is divided into two parts:Firstly, the selective reactions of 1,3-dicarbonyl compounds with N-(a-benzotriazol-l-ylalkyl)methylcarbamate was investigated. With samarium triiodide as the catalyst, the reaction of N-(a-benzotriazol-1-ylalkyl)methylcarbamate with 1,3-dicarbonyl compounds gaveβ-benzotriazolyl 1,3-dicarbonyl compounds with the liberation of methylcarbamate and the reservation of benzotriazolyl. However, with sodium methylate as the catalyst, the reaction of N-(a-benzotriazol-1-ylalkyl)-methylcarbamate with 1,3-dicarbonyl compounds gaveβ-amino 1,3-dicarbonyl compounds with the liberation of benzotriazolyl and the reservation of methylcarbamate.Subsequent study was focused on samarium diiodide mediated reduction ofβ-benzotriazolyl carbonyl compounds. In the system of SmI2-YTHF-HMPA, cyclopropanol was obtained by cleavage of C-Bt inβ-benzotriazolyl ketone;β- alkenylβ- benzotriazolyl ketone also underwent C-Bt bond cleavage but with subsequent free radical migration to produce cyclopent-2-enol; C-C bond cleavage occurred unexpectedly when theβ-benzotriazolyl 1,3-dicarbonyl compounds was used as the substrates, indicating a more fragile C-C bond than the C-Bt bond.