Studies On The Connection Of C-C Bond And The Total Synthesis Of (±)-Crinine And (±)-Maritidine

This thesis finished studies towards" the Construction of some C-C bonds and the Total Synthesis of (±)-Crinine and (±)-Maritidine", including the following four parts.1. Kinetic resolution via semipinacol rearrangement of 2,3-aziridno alcoholsIn research of developing the efficient way to synthesis chiral 2,3-aziridno alcohols and α-quarternary-β-amino ketones (aldehydes) (Mannich bases), the kinetic resolution of 2,3-aziridno alcohols was tested under different conditions for the first time. It was found that the use of the chiral catalyst Ti-[(R)/(S)-BINOL]₂ was efficient. Under the optimized condition, the chiral 2,3-aziridno alcohols and α-quarternary-β-amino ketones (aldehydes) could be obtained with ee up to 50% and 81% respectively.2. Enantioselective addition of phenylacetylene to ketonesThe titanium complexes of the easily prepared chiral ligand were tested under different conditions, such as chiral ligands, solvents and substrates. The easily prepared and recoverable chiral N-sulfonylated β-amino alcohol 20 in combination with Ti(O'Pr)₄ was found to be an effective chiral catalyst for the enantioselective addition of alkynylzinc to ketones, which gave the useful products, i.e. chiral tertiary propargyl alcohols, with moderate to excellent enantioselectivities (up to 92%). Moreover, the obvious solvent effects and the substituent ones of the aromtic ketones were found. This method could be of value for the utility of this kind of important synthetic blocks in enantiomeric excess way.3. KO^tBu-Promoted Three-Component Coupling of Aldehydes and AlkynesA novel KO^tBu-promoted three-component coupling reaction of aldehydes and alkynes has been successfully developed without a transition-metal catalyst, in which the sequential addition/isomerization/ addition processes are involved inone pot. This tandem protocol surely represents an extremely concise, practical, and economical synthesis of (ï¿¡)-1-en-4-yn-3-ols and (Z)-2-en-4-yn-1-ols, which are of versatile utilities in organic synthesis. According to the deuterium-labeling studies, the authors proposed the possible mechanism, in which a 1,3-hydride shift process of propargyl alcohol was proved for the first time. With the same process, a KOfBu-promoted coupling reaction of aliphatic alkynes and aromatic aldehydes was also developed and the product (/3,y-enone) could be obtained with moderate yield. 4. The total synthesis of (±)-Crinine and (±)-Maritidine The synthetic application of the /3-bromo aldehyde 6 with quarternary carbon was tested in the total synthesis of (±)-Crinine and (±)-Maritidine. Commenced with the ethyl 3-oxobutanoate, the key intermediate 11 was efficiently synthesized through 8 steps in an overall 33% yield during the ongoing total synthesis of the target moleculars.