Further studies on hydration of alkynes by the PtCl4–CO catalyst

Abstract

Dedicated to Professor Myron Rosenblum on the occasion of his 75 th birthday in recognition of his outstanding contribution to chemistry AbstractUnder CO atmosphere, between 80 and 120˚C, a glyme solution of PtCl 4 forms a carbonyl compound that promotes hydration of internal as well as terminal alkynes to give aldehyde-free ketones. The catalytic process depends strongly on the electronic and steric nature of the substrates. Part of the carbonyl functions of the catalyst can be replaced by phosphine ligands. Chiral DIOP reacts with the PtCl 4 -CO compound to give a catalyst that promotes partial kinetic resolution of a racemic alkyne. Replacement of part of the CO by polystyrene-bound diphenylphosphine enables to attach the catalyst to the polymeric support. Upon entrapment of the platinum compound in a silica sol-gel matrix, it reacts as a partially recyclable catalyst. A reformulated mechanism for the PdCl 4 -CO catalyzed hydration is suggested on the basis of the present study.

Glymes as versatile solvents for chemical reactions and processes: from the laboratory to industry

“…Yagupolskii et al 278 carried out an aza Curtius rearrangement by reacting N -(trifluoromethylsulfonyl)carboximidoyl chlorides with sodium azide in monoglyme or acetonitrile at −5 to +10 °C to form carbodiimides RN=C=NSO 2 CF 3 . Israelsohn et al 279 reported that the PtCl 4 -CO catalyst could promote the hydration of internal and terminal alkynes in aqueous monoglyme or diglyme to afford aldehyde-free ketones between 80 and 120 °C. The reaction was found strongly dependent on the electronic and steric nature of the alkynes.…”

Similarities and Differences between the “Relativistic” Triad Gold, Platinum, and Mercury in Catalysis

“…The same group reported later that PtCl 4 /CO was a better catalyst for the hydration of alkynes (Scheme 8). [38,89] Moderate yields for both terminal and internal alkynes 59 were found. The mechanism proposed [38] suggests a prereduction of Pt IV to Pt II under CO atmosphere to form the active species 60.…”

“…[38,89] Moderate yields for both terminal and internal alkynes 59 were found. The mechanism proposed [38] suggests a prereduction of Pt IV to Pt II under CO atmosphere to form the active species 60. The catalytic activity observed for PtCl 2 under similar conditions and X-ray photoelectron spectroscopy (XPS) measurements of the final mixture confirms this reduction.…”

“…[38,[86][87][88] Firstly, Jennings and coworkers used Zeises dimer 47 as a catalyst for the hydration of terminal and internal alkynes (Scheme 7). [86] The amount of catalyst needed was low (< 1 mol %) in boiling THF.…”

Ähnlichkeiten und Unterschiede innerhalb der “relativistischen” Triade Gold, Platin und Quecksilber in der Katalyse

“…Anfang der 90er Jahre wurde Pt als ein aktiver Katalysator für die Hydratisierung von Alkinen erkannt 38. 86–88 Als erstes setzten Jennings und Mitarbeiter das Zeise‐Dimer 47 als Katalysator für die Hydratisierung von endständigen und inneren Alkinen ein (Schema ) 86.…”