Isoquinolium salts

The cycloruthenated complex 13 reacts with disubstituted alkynes to afford the novel Ti -aiene Ru(0) complexes 49 which were isolated, characterized by X-ray methods, and oxidatively demetallated by treatment with Cu(II) salts to afford metal-free(7i0"isoquinolium salts 43 (with PF as counterion). Kinetic studies have revealed that the reaction proceeds via insertion of the alkyne into the Ru-C bond and that for this process the rate-limiting step is very similar to that found for the analogous palladium compound. Irradiation or thermal treatment of the cycloruthenated complex 50 with diphenylacetylene yields diphenylindole 51 as product. A similar reaction is observed with the corresponding iron or molybdenum complexes. ... 

In a series of papers, the Langlois group reported multiple strategies toward the construction of manzamine A, 30. An approach to the construction of the ABC tricyclic core framework, 31, employed the Bradsher cycloaddition reaction as the key synthetic step. Thus reaction of isoquinolium salt 32 with ethyl vinyl ether under standard reaction conditions afforded the cycloadduct 33. The advanced intermediate 31 was then generated in six steps. 

Heteroaromatic substrates have been productive targets for both TH and ATH reactions. Quinoline and isoquinolium salts can be reduced by Ru(II) and Rh(III) catalysts by ATH [104, 105]. Chemoselective reductions of quinolines were achieved by TH using IPA with an iridium catalyst (Fig. 31) [106]. 

As the alkaloid was extracted with hexane, acetone, and ethanol, subjected to column chromatography, acidified (AcOH) and then neutralized (NaOH), the cationic form was formulated as a hydroxide salt. However, only two OH groups were detectable on H NMR spectroscopy. Only slight differences were found in the UV spectra taken in methanol [kmax (loge) = 218 (4.68), 302 (4.39), 394 (4.08) nm] and methanol+NaOH [T-max (loge) = 228 (4.66), 310 (4.39) nm]. Three tautomeric forms can be formulated which are shown in Scheme 42. Two of them possess the isoquinolium-7-olate moiety. The H NMR data are presented in Table IV. They indeed unambiguously resemble the cationic species 112. 

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