Thienyl Ethanol

In the absence of strongly polar co-solvents 2-lithiothiophene displays moderate reactivity in alkylations and the reactions have to be carried out at elevated temperatures in the region of 50 °C. Careful control of the temperature is therefore not necessary if the reaction is carried out on a modest scale. The reactivity of 2-lithiothiophene in alkylations can be enhanced enormously by addition of a small amount of HMPT (5-10vol.%) in this case the reaction with butyl bromide proceeds smoothly at 20 °C and is complete within 15 minutes. The organometallic derivative can also be rendered more reactive by adding an equivalent amount of /-BuOK dissolved in THF. Subsequent reaction with butyl bromide proceeds smoothly at —10 to 0 °C. The procedure below can also be applied to prepare other non-volatile alkylthiophenes. We expect secondary alkyl halides to react much less easily dehydrohalogenation may be an important side-reaction, or even the dominant process. 

In a mechanistic sense, the hydroxylation of nucleophilic groups with epoxides resembles the alkylation with alkyl halides. In both cases addition of HMPT or DMSO (the latter if the nucleophile is not too strongly basic) causes an acceleration of the reaction. Reactions with epoxides, however, can also take profit from 

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Dehydration to 2-vinylthiophene is better achieved from 2-(2-thienyl) ethanol with powdered potassium hydroxide in the presence of copper than from 1-(2-thienyl) ethanol. a-Chloro-2-thienylpro-pane undergoes a Wurtz reaction with active iron to give 3,4-di-(2-thienyl) hexane in low yield, which has also been obtained through coupling with n-butyllithium. ... 

Similarly, 3-phenylthieno[2,3-h]thiophene (81) was produced from 1-phenyl-l-(3-thienyl)ethanol (82) [Eq. (28)]. 

Another route to thieno[2,3-c]pyrans begins with 2-(3-thienyl)ethanol and ethyl 3,3-diethoxypropionate. In the presence of a Lewis acid, ethyl (4,5-dihydro-77/-thieno[2,3-r-]pyran-7-yl)acetate is formed in high yield (Equation 34) <2004BMC5277>. 

Benzo[6]thienylethylenes are readily obtained by elimination of water from the appropriate alcohol. For example, 3-vinylbenzo[6]-thiophene is conveniently prepared by heating l-(3-benzo[6]thienyl)-ethanol with potassium hydrogen sulfate469,471 or by heating 2-(3-benzo[6]thienyl)ethanol with molten alkali.470 2-Vinylbenzo[fe]thio-phene is obtained by pyrolyzing the acetate of l-(2-benzo[6]thienyl)-ethanol.466,620 Other benzo[6]thiophene alcohols have been dehydrated by heating them with oxalic acid,483 iodine,358,465,467,528 or potassium hydrogen sulfate,465,467 or alone.349,485... 

One example is the reaction with benzyne of 3-vinylbenzo[/ ]thiophene 102, prepared by dehydration of 2-(3-benzo[b]thienyl)ethanol, to give 11-thiabenzo[a]fiuorene 103 (65AJC1781). 

The reaction of l,l-bis(2-thienyl)ethanol 221 with TONE at room temperature afforded a white crystalline compound identified as cycloadduct 223 in quantitative yield (90H1873). The formation of 223 is easily understood as a [4 + 2]-cycloaddition of l,l-bis(2-thienyl)ethylene 222, formed by dehydration of alcohol 221 and TCNE. The reaction was unusually fast, it took place in less than 15 minutes and did not need any source of heat or light to be promoted. Since other vinylthiophenes participate in Diels-Alder reactions to give aromatic cycloadducts under rather severe conditions (Section II,A,5), the authors suggested that the reaction... 

Vinylthiophene has been prepared by the dehydration of a-(2-thienyl)ethanol,3-6 by the condensation of vinyl chloride with 2-thienylmagnesium bromide in the presence of cobaltous chloride,6 and by the dehydrochlorination of cc-(2-thienyl) ethyl chloride.7... 

Thienyl)ethanol as a starting material will give monomers with an ether linkage in the substituent at the 3-position. Such monomers, once polymerized, have exhibited the ability to complex cations such as Li in a loose crown ether type structure [70]. This in turn leads to enhanced conductivity of the polymer when such cations are part of the supporting electrolyte. An added benefit of electropolymerization of polythiophene originates from the fact that sulfur has a tendency to physisorb to metals such as gold and platinum, which are electrode materials. Hence they may enhance the adsorption of polymer to the electrode and thus improve the physical stability of the system, as well as the extent of polymer/electrode interaction. The synthesis of these type of monomers (e.g., 60) is shown in Scheme 10-28. 

Cyanurate-isocyanurate rearrangements are well known <83IZV2369>. An application of the thermal rearrangement (230 °C) to an amine synthesis has been utilized in the preparation of 2-(2-thienyl)ethylamine from 2-(2-thienyl)ethanol in 77% overall yield. A mechanism for the tetra-butylphosphonium bromide-catalyzed rearrangement was proposed (Scheme 34) <93SC1307>. 

Vinylthiophene has been prepared by the dehydration of a-(2-thienyl)ethanol, by the condensation of vinyl chloride with... 

A 1 1 molar mixture of monomers 2-(3-thienyl)ethyl hexanoate and 2-(3-thienyl)ethanol can be polymerized by chemical oxidation with FeCU and gives a soluble ester-functionaUzed PAT with an electrical conductivity in the doped state of 4.9 X 10 S cm [583,584]. Thiophene, 3-methylthiophene, bithiophene and terthiophene are polymerized in the channels of molecular sieve zeolite hosts. Conducting polymers can be isolated after dissolution of the zeolite host in HF [615]. 

Novel materials were prepared by electrochemical copolymerization of thiophene with thiophene-3-acetic acid (XV) [49], The incorporation of the —COOH group allows for the loading of metal catalysts into these systems. These copolymers were soluble and had high degrees of polymerization (>2000). Copolymers between 3-methylthiophene and ferrocene esters of 2-(3-thienyl-ethanol) with varying alkyl chain lengths have been prepared (XVI) [50]. 

A series of N-substituted-2-amino-l-(thienyl)ethanols were evaluated as 3-blockers and found to be less potent than propranolol as inhibitors of the tachycardic response to isoproterenol.21 a series of heterocyclic pro-panolamines had 3-blocking activity, the most potent ( ) having ten times the activity of propranolol on the guinea pig atrial strip.22... 

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