Thiophenes 2,3-dihydro-3-hydroxy- from

H- 1-Benzothiin, 3-bromo-4-hydroxy-3,4-dihydro-dehydration, 3, 908 2//-1-Benzothiin, 3,4-dibromo-thiophene synthesis from, 4, 902 277-1-Benzothiin, 3,4-dihydro-acylation, 3, 908 sulfilimines from, 3, 905 277-1-Benzothiin, 4-ethoxy-reactions... 

Figure 8 outlines possible routes leading to cysteine specific products via 1-deoxypentosone. Under the chosen reaction conditions, (180 °C H-O) norfuraneol is further transformed via 4-hydroxy-5-metnyl-3-(2H)-thiophenone and 2-methyl-3-(2H)-thiophenone, into 2-methyl-3-mercapto-thiophene and 2-methylthiophene, respectively. Norfuraneol is a methylene active compound, which undergoes aldolcondensation with carbonyls forming colored nonvolatile products. 2-Mercaptopropionic acid may be formed from the mercaptoketone by oxidative cleavage. By this route 2-methyl-3-thiolanone and 2-methyl-4,5-dihydro-thiophene may result. 

In Figure 8.11 the isomeric urethane derived from ProDOT-OH (hydroxy-3,4-propylenedioxy-thiophene, 3,4-dihydro-2H-thieno[3,4-b][l,4]dioxepin-3-ol) instead of EDOT-CH2OH is also depicted (formula B). ProDOT-OH is a typical byproduct of EDOT-CH2OH when synthesized from epibromohydrin and 3,4-dihydrox5dhiophene-2,5-dicarboxylic acid esters, and it is difficult to separate. More synthetic details are given in Chapter 12. Due to the mixture of two components, the results must be considered as only tentative. 

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