The first total synthesis of ($-$)-hapalindole G, a member of novel chlorine- and isonitrile-containing hapalindoles from the cultured cyanophyte Hapalosiphon fontinalis, is accomplished. Our 21-step synthesis of ($-$)-hapalindole G from ($-$)-carveol features a stereospecific introduction of chlorine next to a quaternary center via cleavage of the cyclopropane intermediate and facile elaboration of the indole moiety through a conjugate addition of lithium methyl methylthiomethyl sulfoxide to an enone followed by hydrolysis of the resultant adduct. The absolute configuration of ($-$)-hapalindole G has therefore been confirmed on the basis of the specific rotation of our synthetic sample.
Also described herein is a novel tin-mediated radical indole synthesis by using o-isocyanostyrene derivatives as starting materials via 2-tri-n-butylstannyl-3-substituted indoles as intermediates. The 2-tri-n-butylstannyl-indoles were also subjected to the one-pot Stille coupling reaction and iodination. The iodoindoles were capable of further manipulation. Our efficient synthesis paves the way for a facile construction of a variety of 3- or 2,3-substituted indoles from readily accessible isonitriles.
| Identifer | oai:union.ndltd.org:RICE/oai:scholarship.rice.edu:1911/16719 |
| Date | January 1994 |
| Creators | Chen, Xiaoqi |
| Contributors | Fukuyama, T. |
| Source Sets | Rice University |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | 257 p., application/pdf |
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