Catalytic Hydration of Alkynes and Its Application in Synthesis

Abstract

The catalytic addition of water to alkynes (hydration) generates valuable carbonyl compounds from unsaturated hydrocarbon precursors. Traditional mercury(II) catalysts hydrate terminal alkynes with Markovnikov selectivity to methyl ketones. Much research has been devoted to finding catalysts based on less toxic metals, the most promising being gold(I), gold(III), platinum(II), and palladium(II). Catalytic anti-Markovnikov hydration of terminal alkynes to aldehydes has been realized in an efficient manner with ruthenium(II) complex catalysts. The present review article lists known hydration catalysts and discusses applications of catalytic hydration to different classes of substrates, with an emphasis on functional group tolerance and regioselectivity. 6 Reactions Related to Catalytic Alkyne Hydration 7 Conclusions and Outlook

An efficient access to novel 2H-pyrazino[2,1-b]quinazoline-1,6-diones via intramolecular alkyne hydroamination

“…Among the numerous conditions that have been used for alkyne hydration, 4 To briefly examine the scope of this route, we also employed an N-alkylamide (N-ethyl-4-oxo-3-(prop-2-yn-1-yl)-3,4-dihydroquinazoline-2-carboxamide, 2b) as well as the corresponding primary amide (2c) as substrates in the mercury(II)-catalyzed cyclization reaction. In both cases, the desired tricyclic pyrazinones of type 3 were obtained in satisfactory yields after the usual work-up and purification procedure.…”

“…2,3 In view of the reported side reaction, 1 leading to the fused pyrazinone (see above), we envisaged our propargyl-substituted quinazolinonecarboxamides as potential precursors for novel tricyclic pyrazinones, although such compounds had never been observed in the cycloaddition reactions of the anilides when Hendrickson's reagent was used as the promotor. Nevertheless, we anticipated that subjecting these amides to reaction conditions that are typically employed for the anti-Markovnikov hydration of alkynes 4 should permit the desired ring closure reaction between the amide nitrogen and the propargyl residue. Here, we wish to report on the application of this concept (known as alkyne hydroamination triggered cyclization 5 ) for the convenient synthesis of a small series of novel 3-methyl-2H-pyrazino[2,1-b]quinazoline-1,6-dione derivatives that represent an interesting new molecular scaffold.…”

Ruthenium piano-stool complexes bearing imidazole-based PN ligands

“…5 Other metal-based catalysts which catalyze the Markovnikov as well as anti-Markovnikov hydration include NaAuCl 4 , RuCl 3 and [Ru(III)(EDTA-H)Cl], RhCl 3 , PtCl 4 and the Zeise dimer [{PtCl 3 (CH 2 =CH 2 )} 2 ], just to name a few. 6,7,8,9,10,11,12,13 Besides these homogenous catalysts also heterogenous catalyst systems are used. 14,15,16 The first ruthenium(II) complex to be known to catalyze the anti-Markovnikov hydration was a phosphine complex described by Tokunaga and Wakatsuki.…”

One-Pot Formation of Functionalized Indole and Benzofuran Derivatives Using a Single Bifunctional Ruthenium Catalyst

“…These are usually sufficiently electrophilic for nucleophilic attack by water [2], alcohol [3,4], phenols [5], amines [6,7] and many other nucleophiles. A wide variety of transition metal based catalysts have been reported to catalyze alkyne hydration [8], alkynylaryl amine [9][10][11][12][13][14][15] and -phenol [16][17][18][19] cyclization, etc. However, there has not been any report, to the best of our knowledge, of one catalyst capable of carrying out cyclization and hydration in the same reaction flask.…”