Iridium hydroalkoxylation

C-M bond addition, for C-C bond formation, 10, 403-491 iridium additions, 10, 456 nickel additions, 10, 463 niobium additions, 10, 427 osmium additions, 10, 445 palladium additions, 10, 468 rhodium additions, 10, 455 ruthenium additions, 10, 444 Sc and Y additions, 10, 405 tantalum additions, 10, 429 titanium additions, 10, 421 vanadium additions, 10, 426 zirconium additions, 10, 424 Carbon-oxygen bond formation via alkyne hydration, 10, 678 for aryl and alkenyl ethers, 10, 650 via cobalt-mediated propargylic etherification, 10, 665 Cu-mediated, with borons, 9, 219 cycloetherification, 10, 673 etherification, 10, 669, 10, 685 via hydro- and alkylative alkoxylation, 10, 683 via inter- andd intramolecular hydroalkoxylation, 10, 672 via metal vinylidenes, 10, 676 via SnI and S Z processes, 10, 684 via transition metal rc-arene complexes, 10, 685 via transition metal-mediated etherification, overview,... 

Iridium(ni) hydrides, such as (98), proved to be air-stable active catalysts for intramolecular hydroalkoxylation and hydroamination of internal alkynes with proximate nucleophiles (e.g. 96). The cyclization follows the 6-endo-dig pathway with high preference (when regioselectivity is an issue).125... 

An iridium(m) hydride catalyzed intramolecular alkyne hydroalkoxylation can be used to construct isochromans 545 bearing a C(3)-spiroacetal moiety (Equation 226) <2005OL5437>. Novel isochromans bearing an array of C(3)-spiroacetal moieties are accessible via the hydroboration of alkynediols with disiamylborane followed by treatment of the resulting alkenylboron compounds with alkaline hydrogen peroxide <1998CL81>. 

As an alternative, iridium complexes show exciting catalytic activities in various organic transformations for C-C bond formation. Iridium complexes have been known to be effective catalysts for hydrogenation [1—5] and hydrogen transfers [6-27], including in enantioselective synthesis [28-47]. The catalytic activity of iridium complexes also covers a wide range for dehydrogenation [48-54], metathesis [55], hydroamination [56-61], hydrosilylation [62], and hydroalkoxylation reactions [63] and has been employed in alkyne-alkyne and alkyne - alkene cyclizations and allylic substitution reactions [64-114]. In addition, Ir-catalyzed asymmetric 1,3-dipolar cycloaddition of a,P-unsaturated nitriles with nitrone was reported [115]. 

Iridium complexes have also been shown to catalyze the tandem cycloisome-rization/hydroalkoxylation of bis-homopropargylic alcohols to give furanyl and... 

Intramolecular hydroalkoxylation of internal alkynes containing proximate oxygen nucleophiles was catalyzed by iridium hydride complex [48] (Scheme 29). The cyclization of 2-alkynylbenzyl alcohols follows highly selective 6-endo-dig regiochemistry for both alkyl and aryl substituents on the multiple bond. Cyclization of substrates having two OH groups gave spiroacetal derivatives. When... 

Messerle BA, Vuong KQ (2007) Rhodium- and iridium-catalyzed double hydroalkoxylation of alkynes an efficient method for the synthesis of O, 0-acetals catalytic and mechanistic studies. Organometallics 26 3031-3040... 

Li X, Chianese AR, Vogel T, Crabtree RH (2005) Intramolecular alkyne hydroalkoxylation and hydroamination catalyzed by iridium hydrides. Org Lett 7 5437-5440... 

Messerle BA, Vuong KQ (2006) Synthesis of spiroketals by iridium-catalyzed double hydroalkoxylation. Pure Appl Chem 78 385-390... 

Fjermestad T, Ho JHH, Macgregor SA, Messerle BA, Tuna D (2011) Computational study of the mechanism of cyclic acetal formation via the iridium(I)-catalyzed double hydroalkoxylation of 4-pentyn-l-ol with methanol. Organometallics 30 618-626... 

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