Total Syntheses Of β-carboline Alkaloids Dichotomines A-D, Pyridindolol,Pyridindolol K1and Pyridindolol K2

β-carboline alkaloids widely exist as natural resources. Every year many new β-carboline alkaloids have been isolated and lots of them exhibit various bioactivities. Total syntheses of β-carboline alkaloids dichotomines A-D, pyridindolol, pyridindolol Kl and pyridindolol K2were studied in this thesis. All the procedures (reaction conditions, work-up and purification) were studied in detail.(1) Synthesis of dichotomines A-D from (R)-glyceraldehyde acetonide. Starting from (R)-glyceraldehyde acetonide and L-tryptophan methyl ester,(-)-dichotomines A-D were obtained by9-13steps in24%,32%,35%and33%respective overall yields. The absolute configuration of the stereogenic center of (-)-dichotomine A was reconfirmed as (S) based on the X-ray crystallographic analysis of compound Ⅱ-49, while absolute configurations of the stereogenic centers of (-)-dichotomines B-D were revised as (R).(2) Synthesis of dichotomines A-D from (S)-glyceraldehyde acetonide. Total syntheses of (-)-dichotomines A-D starting from L-tryptophan methyl ester and (S)-glyceraldehyde acetonide were achieved, with respective total yields of39%,66%,74%and68%by4-9steps. In comparision with the above synthetic route, this route is more atom economic, featuring with shorter synthetic steps and higher overall yields.(3) Synthesis of dichotomines A-D from L-lactic acid.(-)-Dichotomines A-D were obtained from L-tryptophan methyl ester and L-lactic acid in5-7steps with overall yields of21%,44%,49%and46%, respectively. This synthetic route featured a Bischler-Napieralski reaction and a Sharpless Asymmetric Dihydroxy reaction.(4) Synthesis of (R)-(-)-pyridindolol,(R)-(-)-pyridindolol K1and (R)-(-)-pyridindolol K2from (S)-glyceraldehyde acetonide. Starting from readily available L-tryptophan methyl ester and (S)-2,3-O-isopropylidene-L-glyceraldehyde,(R)-(-)-Pyridindolol was synthesized via5steps in66%overall yield,(R)-(-)-pyridindolol K1was synthesized via7steps in41%overallyield and (R)-(-)-pyridindolol K2was synthesized via6stepsin55%overall yield.