Iwao indole synthesis

Indole Ring Synthesis From Natural Products to Drug Discovery, First Edition. Gordon W. Gribble. 2016 John Wiley Sons, Ltd. Published 2016 by John Wiley Sons, Ltd. 

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While the Iwao indole synthesis has yet to grab the attention of the synthetic community, Fukuyama and Chen used a related Pummerer reaction, 3-4, in their synthesis of the marine alkaloid (-)-hapalindole G, as shown in Scheme 2 [6],... 

Closely related to the Iwao indole synthesis (Chapter 33) is the discovery by Hewson and colleagues, who found that ortfto-sulfonamide ketene dithioacetal 5-oxides 1 readily cyclize to the corresponding 2-thiomethylindoles 2 upon treatment with hydrochloric acid in the presence of hydrogen sulfide (Scheme 1) [1]. The hydrogen sulfide prevents the... 

Iwao s group has independently established an efficient methodology for the synthesis of 3,4-differaitially substituted indoles. Their contributions in the total syndiesis of ot alkaloids are also reviewed. 

Iwao et d. introduced an efficient methodology ftH the synthesis of 3,4-disubstituted indoles 113 (57). Their strategy comprises two sequential steps 1) selective functionalization of l-silyl-3-dimethylaminomethylindole (111) at the 4-position by directed lithiation, followed by quenching with electrophiles, for the preparation of 4-dimethylamino-substituted indole 112 (58) 2) substitution of the dimethylamino group of 112 for various nucleophiles giving 113 upon desilylation through quatemization followed by a fluoride ion-induced elimination-addition reaction (Scheme 17) (59). 

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