Some reactions of acetylenic alcohols
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Part I - Reactions of 1-methoxy-2,2-dimethyl-3-phenylhex-4-yn-3-ol (B7) with lithium aluminium hydride in a range of ethers as solvent gave only two products: 1-methoxy-2,2-dimethyl-3-phenylhexa-3,4-diene (C4) and (E)-1-methoxy-2,2-dimethyl-3-phenylhex-4-en-3-ol (C3). The relative yields of the products varied with solvent as well as with reaction conditions. However, deuterium labelling revealed that the ratio of hydride attack at the C4 and C5 of the alkyne function remained constant. Reactions of compound (B7) in benzene as solvent were found to give reasonable yields of the two products (C3) and (C4). Reactions of 1-methoxy-3-phenylhex-4-yn-3-ol (B4) with lithium aluminium hydride in diethyl ether gave 1-methoxy-3-phenylhexa-4,5-diene (C5), and (E)-1-methoxy-3-phenylhex-4-en-3-ol (C6) as the predominant product. In the tetrahydrofuran reactions at room temperature only compound (C6) was identified. Under more vigorous conditions, the alkynol (B4) was converted into two cyclopropane derivatives (C7) and (C8) in addition to the major product (C6). The mechanisms for the formation of these cyclopropane derivatives are discussed. Part II - Reactions of 4-t-butylcyclohexanone and its methylated analogues (2.2, 2.7, 2.9, 2.10) with propynylmagnesium bromide or propynyllithium gave the alkynols (B8, B9, B10, B11, B12, B13, B14, B15). The stereochemistry of these reactions is discussed. The reductions of the above alkynols with lithium aluminium hydride in a range of ethers as solvent were investigated. Compounds (B8-13) reacted to give the corresponding allene, (Z)-alkenol and (E)-alkenol; (D1-18). The reactions of compound (B14) gave allene (D19) and (E)-alkenol (D21), no cis alkenol was detected. Allene (D19) was produced predominantly. Alkynol (B15) reacted to give the two usual products (D22, D24) but, in addition gave the secondary alcohol (B16). The mechanism of formation of compound (B16) is discussed. The reactions of alkynols (B13, B14, B15) in diethyl ether as solvent gave the corresponding allenic compound (D16, D19, D22) as the sole product.