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I'm not an expert teacher or lecturer of chemistry. I was only a student from SMA NEGERI 15 SURABAYA who had been one of the Bronze Medalist Participants of Olimpiade Sains Nasional X (2011) of Chemistry In Manado, North Sulawesi, 11 - 16 September 2011 and graduated in 2012. Now, I'm studying at Universitas Airlangga in Surabaya, Indonesia. I do love chemistry and I would like to help them who had difficulties in studying chemistry. That's why, please understand me if you found some misconcepts in my entries. Suggestions are always necessary in order to develop this blog. And I'm sorry because my English isn't so well.

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Saturday, May 31, 2014

Organic Chemistry Problems: Acid-Catalyzed Domino Reactions of Tetraarylbut-2-yne-1,4-diol

A cascade reaction or tandem reaction or domino reaction is a consecutive series of intramolecular organic reactions which often proceed via highly reactive intermedietes. Domino reactions are a powerful tool for the elegant construction of complete molecules from simple substrates with high atom economy.

The reaction of tetraarylbut-2-yne-1,4-diol with electron-rich aromatic compounds at room temperature under p-TsOH catalysis, affords substituted polycyclic aromatic indene derivatives through a domino reaction involving the formation of a cationic allerylium intermediate. Given an organic reaction as follows:

a. Suggest a good synthesis of tetraphenylbut-3-yne-1,4-diol as follows:

b. Propose a mechanism of the acid-catalyzed one-pot synthesis of furans from trisubstituted but-2- yne-1,4-diol as follows:

c. The one-pot synthesis of 1-vinylidenenaphthofurans from tetraarylbut-2-yne-1,4-diol includes Claisen Rearrangement and Enolization Process. Propose a mechanism of the reaction as follows:

d. Propose a mechanism for the formation of 1H-Indene Dye from tetraphenylbut-2-yne-1,4-diol and 1-Naphtol and explain the differences between question c and d.

e. One of the compounds from those reactions above has the following data:

Shift (ppm) of 1H-NMR (400 MHz, CDCl3)
δ 7,59
(d, J = 7-9 Hz, 8H)
δ 7,39-7,23
(m, 12H)
δ 2,86
(s, 2H, -OH)

MS Data: Mr = 390,47, Formula: C28H22O2
Predict the structure of that compound and explain your answer.

Wikipedia: Cascade Reaction

Céu M. Sousa et al. (2014). Acid-Catalyzed Domino Reactions of Tetraarylbut-2-yne-1,4-diols. Synthesis of Conjugated Indenes and Inden-2-ones. J. Org. Chem., Article ASAP.  DOI: 10.1021/jo500907z

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