Synthetic Studies of Substituted Pyridine Aldehydes as Intermediates for the Synthesis of Toddaquinoline, Its Derivatives and Other Natural Products
摘要:
The synthesis of substituted 2-bromopyridine aldehydes as intermediates in our planned approach to toddaquinoline, its derivatives and other natural products is reported. The DMF-formylation method of pyridine ring, the Vilsmeier-Haack procedure and the bromination of pyridine ring respectively, were studied in order to synthesize the above mentioned compounds. The successful methods (DMF-formylation and bromination of pyridine ring) provided the 2-bromo-4-formyl-5-tosyloxypyridine Ib and 5-benzyloxy-2,4,6-tribromonicotinaldehyde Ia under relatively mild conditions and in good yields.
[4+2]cycloaddition of electron‐rich 5‐benzyloxy‐2‐pyridone (1) with phenylvinyl sulfone furnished, after functional group transformation, 2 in a syn/anti ratio of 3/7. Deprotonation with LDA provided the thermodynamic stable 2a. The α‐sulfonyl carbanion can be alkylated to 4. During reductive desulfonylation complete epimerisation to 5 occured. Synthesis of 5b was also accomplished by conjugate addition
A Facile Entry to the 2-Azabicyclo[2.2.2]octane-6-one Skeleton via [4+2]-Cycloaddition
作者:C. Herdeis、C. Hartke
DOI:10.1055/s-1988-27472
日期:——
2-Aza-bicyclo[2.2.2]octane-6-one derivatives are prepared from 5-hydroxy-2-pyridone via [4+2]-cycloaddition with phenyl vinyl sulfone as an ethylene equivalent. Complete regiospecificity is observed. The exo-endo 15 ratio of the adducts is 7:3. A four step reaction sequence affords 2-aza-6-dimethoxybicyclo[2.2.2]octane, a starting material in the synthesis of desethylibogamine.
We report the total synthesis of (±)-aspidophylline A, one of many complex furoindoline-containing alkaloids that has not been synthesized previously. Our route features a number of key transformations, including a Heck cyclization to assemble the [3.3.1]-bicyclic scaffold as well as a late-stage interruptedFischerindolization to install the furoindoline and construct the natural product's pentacyclic
我们报告了 (±)-aspidophylline A 的全合成,这是以前未合成的许多复杂的含有呋喃二氢吲哚的生物碱之一。我们的路线具有许多关键转化,包括组装 [3.3.1]-双环支架的 Heck 环化以及后期中断的 Fischer 吲哚化以安装呋喃二氢吲哚并构建天然产物的五环框架。
HERDEIS, C.;HARTKE-KARGER, ARCH. PHARM., 322,(1989) N0, C. 653
作者:HERDEIS, C.、HARTKE-KARGER
DOI:——
日期:——
HERDEIS, CLAUS;HARTKE-KARGET, CLAUDIA, LIEBIGS ANN. CHEM.,(1991) N, C. 99-104