Transition metal complexes, gold

A unique method to generate the pyridine ring employed a transition metal-mediated 6-endo-dig cyclization of A-propargylamine derivative 120. The reaction proceeds in 5-12 h with yields of 22-74%. Gold (HI) salts are required to catalyze the reaction, but copper salts are sufficient with reactive ketones. A proposed reaction mechanism involves activation of the alkyne by transition metal complexation. This lowers the activation energy for the enamine addition to the alkyne that generates 121. The transition metal also behaves as a Lewis acid and facilitates formation of 120 from 118 and 119. Subsequent aromatization of 121 affords pyridine 122. 

Slovokhotov, Yu.L. and Struchkov, Yu.T (1984) X-ray crystal structure of a distorted tetrahedral cluster in the salt [(Ph P)4Au4N] BF4 . Geometrical indication of stable electronic configurations in post-transition metal complexes and the magic number 18-e in centred gold clusters. Journal of Organometallic Chemistry, 177, 143-146. 

A number of transition metal complexes will catalyze the dehydrogenative coupling of organotin tin hydrides, R SnI I, to give the distannanes, RjSnSnRj.443 These metals include palladium,449 gold,450, hafnium,451 yttrium, and ruthenium.452 The catalyst that is most commonly used is palladium, often as Pd(PPh3>4, and the most active catalysts appear to be the heterobimetallic Fe/Pd complexes, in which both metals are believed to be involved in the catalysis.443... 

Lazar, M. and Angelici, R.J. (2005) Gold metal-catalyzed reactions of isocyanides with primary amines and oxygen analogies with reactions of isocyanides in transition metal complexes. J. Am. Chem. Soc., 128, 10513. 

The excellent ability of late transition metal complexes to activate alkynes to nucleophilic attack has made them effective catalysts in hydroamination reactions. The gold(l)-catalyzed cyclizations of trichloroacetimidates 438, derived from homopropargyl alcohols, furnished 2-(trichloromethyl)-5,6-dihydro-4f/-l,3-oxazines 439 under exceptionally mild conditions (Equation 48). This method was successfully applied to compounds possessing aliphatic and aromatic groups R. With R = Ph, cyclization resulted in formation of 439 with complete (Z)-stereoselectivity <2006OL3537>. 

The use of ylides as ligands has allowed a number of gold(III) complexes containing four organic groups to be isolated. A review of ylide complexes of several transition metals, including gold, has appeared (48), and such species were featured briefly therein. 

Coordination Chemistry History Coordination Numbers Geometries Copper Inorganic Coordination Chemistry Gold Organometallic Chemistry Halides Solid-state Chemistry Photochemistry of Transition Metal Complexes. 

It is surprising that transition metal complexes containing ferrocenyl thio-late ligands (FcS) have not been studied in detail so far. The only examples are gold complexes such as (Fc-S)Au(PPh3) [86], [(FcS)Au2(PPh3)2](BF4) [86, 183], [(Ph3PAu-S)fc-S-]2 (Scheme 5-18) [90], and [(FcS)Au(nBu)2]3 [86],... 

The gas phase reaction between carbon monoxide and dichlorine catalysed by gold(III) chloride or transition metal complexes is discussed in Section 5.1.5.4. 

---