Abstract
AbstractThe first part of this thesis describes the use of the Diels-Alder cycloaddition reaction between diester 36 and diene 52 for the purpose of achieving the total synthesis of natural products of a high degree of structural complexity. Specifically, the first part details the total synthesis of (±)-teuscoloride (44).Starting with dienophile 36, Diels-Alder cycloaddition of which with diene 52 furnished tricyclic enone 60. Subsequent 1,4-addition of a methyl group onto the corresponding acetate furnished ketone 63. Base hydrolysis of 63 then allowed for the generation of ketone 51 which was subsequently subjected to a series of reactions including hydrogenation, Jones oxidation, and an acid promoted cyclization and dehydration to give lactone 67. Towards the total synthesis of 44, the intermediate 67 was reduced by Dibal-H in a highly regioselective manner to furnish furan 46. Oxidation of the hydroxyl of furan 46 was achieved by treatment with Fetizon’s reagent to give aldehyde 47, treatment of which with 3-furyllithium followed by base allowed for the completion of the total synthesis of (±)-montanin A (39). (±)-Montanin A (39) was further oxidized with PDC to yield lactone 81 which was subsequently dehydration by treatment with pTSA to complete the total synthesis of (±)-teuscoloride.The second part of this thesis reports herein a convenient general procedure for the 1,3-allylic alcohol transposition, based on the lithium naphthalenide (LN) induced reductive elimination of epoxy mesylate. The facility of this procedure lies in the ease of preparation of epoxy mesylates from the corresponding allylic alcohol and the subsequent reductive elimination to fulfill the purpose of 1,3-oxygen transposition. For example, epoxidation of the allylic alcohol 1a with m-CPBA in CH2Cl2, followed by treatment of the resulting epoxides 2a with triethylamine and methanesufonyl chloride resulted in the formation of epoxy mesylates 3a. The sequential reductive elimination reaction of 3a was found to occur readily under mild conditions using LN as a reducing reagent to generate the rearrangement product 4a. The results of these and the above mentioned research and studies constitutes the body of this thesis.