C26 DIALKYL AND SPIROALKYL ANALOGS OF MARCFORTINE A
摘要:
The C26 dimethyl dioxepinoindole ring found in marcfortine A is unique among natural products. In order to ascertain the importance of the dimethyl moiety to anthelmintic activity, we prepared a variety of C26-dialkyl and spiroalkyl analogs. They include cyclobutyl, cyclohexyl, diethyl, and ethyl-methyl derivatives. This communication describes the synthesis of these compounds. (C) 1997 Elsevier Science Ltd.
Conceptually novel homolytic substitutions (SH2) of ClCp2Ti−O bonds with benzylic, secondary and tertiary alkyl radicals are described. The intermediates and crucial transition structures were studied by DFT methods. The resulting atom economical radicaltandemreaction can be utilized for the synthesis of structurally complex tetrahydrofurans from simple starting materials and is therefore of interest
Racemic 2,6-dimethyioctyl formate (1), a synthetic analog of the aggregation pheromone of two species ofTribolium beetles, has been obtained in six steps and in 28 % overall yield starting from methyl ethyl ketone, vinyl bromide, and 2-methylpropenal. The key step of the synthesis is the sigmatropic [3,3]-rearrangement of 4-ethyl-2,4-dimethyl-1,5-hexadien-3-ol (5) to 2,6-dimethyl-5-octenal (6).