Aminophenethyl alcohols

The2-aminophenethyl alcohols resulting from condensation of orr/ici-nitrotoliienes are good precursors for preparation of indoles. Watanabe and co workers have developed ruthenium-catalyzed dehydrogenadveiV-heterocyclizadon for synthesis of indoles and other hereto cycles from 2-aminophenethyl alcohols or 2-nitrophenylethyl alcohols fEq. 10.52. The oxidadve cycli-zadon of 2-aminophenethyl alcohols are also catalyzed by Pd-based catalysts. ... 

With the more active RNi cathode, the electrohydrogenation is much less selective and hydrogenolysis of the benzylic C-O bond of 26 occurs to an appreciable extent to give / -aminophcnethyl alcohol (28) and cyclohexanol (30) in 70% yield (30% yield of aminodioxolane 28) after 8.9 F/mol (15). The hydrogenolysis of the benzylic C-O bond gives the intermediate hemiketal 27 which cleaves to p-aminophenethyl alcohol (30) and cyclohexanone (29) (Scheme 9). Cyclohexanone is electiohydrogenated further to cyclohexanol (30). 

Indole synthesis.2 2-Aminophenethyl alcohols cyclize to indoles in refluxing toluene in the presence of this Ru(II) catalyst in 75-100% yield. 

Iminodithiazoles 108 prepared from Appel salt 20 and o-aminobenzyl- and o-aminophenethyl-alcohols can be converted into 3,1-benzoxazine 109a and 3,1-benzoxazepine 109b by treatment with sodium hydride in THF (Equation 22) <1997SL704>. The oxygen-containing heterocycles 109 are apparently formed by cyclization of the alkoxide from dithiazole 108 onto the imine bond, followed by loss of S2 with generation of the cyano group. 

Several investigators have developed the reductive cyclization of o-nitrostyrenes into an efficient synthesis of indoles. Thus, research by the groups of Watanabe [480], Soderberg [481], and Cenini [482] have established this reductive Pd-catalyzed TV-het-eroannulation reaction as a viable and powerful route to simple indoles and fused indoles (411) as shown below. In addition, Soderberg has shown the application of this method to carbazolones [481d], natural p-carbolines [481e], and the carbazole alkaloid murrayaquinone A [48If]. Ohta described the related Pd-catalyzed cyclization of o-aminophenethyl alcohol to indole in 78% yield [483]. 

S. Baek, J. J. Ree, M. Ree, Synthesis and characterization of conducting poly(aniline-co-o-aminophenethyl alcohol)s, /o r a/ of Polymer Science Part A - Polymer Chemistry 2002, 40, 983. 

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