Indole, pyrrolo

Nakagawa devised a concise synthetic route to physostigimine (169) where the key step involves the alkylative cyclization of 1,3-dimethylindole (167) with (Z)-aziridine catalyzed by Sc(OTf)3 and TMSC1 to give 168, which, in turn, can be converted into 169 . A similar asymmetric approach to this natural product was also developed by these authors via treatment of tryptophan carbamates with the Corey-Kim reagent so as to induce intramolecular cyclization to the pyrrolo-indole skeleton . 

The treatment of /Vb-methoxycarbonyl-L-tryptophan methyl ester (9) with trifluoroacetic anhydride in trifluoroacetic acid gave directly the A -trifl uoroacetyl cyclic tautomer with excellent diastereoselectivity [90% yield, endo/exo 97 3 ( ll NMR)]60. Furthermore, pure A a-sulfonyl-entfo-derivatives (X-ray) were prepared from lo206,61 and were employed to prepare homochiral a-, / -, and a, -substituted tryptophan derivatives and pyrrolo[2,3-b]indole alkaloids206 59 62. Similarly, the /Va-acetyl-enc/o-pyrrolo-indole 10 was used for the synthesis of 5-substituted L-tryptophan derivatives63,64. 

Several ingenious approaches have been described for the elaboration of the pyrrolo-indole unit (strictly a benzo[l,2-fc 4,3-( ]dipyrrole) three of which are present in the potent anti-tumour compound CC-lObS the approach shown here uses the van Leusen approach (16.16.1.3)." °... 

Condensed and other heterocyclic systems Nitrogen systems. Pyridazine 67 reacted with 10 and aromatic aldehydes to yield phthalazines 68. Arylideneindolinones 69 underwent Michael addition with 10. By subsequent cyclization pyrrolo-indoles 70 were formed Conjugated azoalkenes 71 and 10 gave pyrrolopyrroles 11. ... 

The pyrrolo-indole (712) forms the tryptophan derivative (713) by the action of methanolic sulphuric acid/ ... 

Recently, the tryptophan rearrangement step of the biosynthetic pathway to Prn, catalyzed by PrnB, was confirmed by the rearrangement of a pyrrolo-indol derivative obtained from tryptophan under basic condition to an aminoarylpyrrol similar to the enzyme-catalyzed step [37]. 

Interest in the synthesis of the mitomycins has resulted in a variety of procedures for the preparation of pyrrolo-indoles and related structures. Now Ban and his colleagues have reported a biomimetic route to the mitosane skeleton which involves a novel retro-aldol type of ring-opening reaction followed by a trans-annular cyclization (Scheme 102). A mitosane-like compound is available via... 

Reductive cyclization of aromatic hydroxylamines in the presence of ethyl 6-oxohex-2-ynoate leads to pyrrolo-indoles in moderate yields (Scheme 104). ... 

Electrophilic substitution reactions have been studied for all the four isomeric pyrrolo-indoles, particularly Vilsmeier-Haack, Mannich, azocoupling and acetylation reactions. Some conversions have been carried out in side chain in order to obtain biologically active compounds. 

R) -a-pyrrolidinyl tetrazole 1119 pyrroline-1-carbonyl group 1249 pyrrolo-indole core 1104 -tricyclic 1104 pyrroloindoline 750... 

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