Pd /acetylene

Reagents (i) TMS-acetylene, Pd(PPh3)2CI2, Cu, Et3N, dioxane (ii) allylic halide, K2C03, DMF (iii) Co2(CO)8 then heat or NMO... 

Fritsch Pulverlsette planetary ball mill, grinding beakers (45 mL, agate. ZrO-J, balls (6x 15mm), SOOrpm, 20min, Arl acetylene Pd(OAc)2 DABCO 2 2.5 0.05 2.5, ALJCs grinding auxiliary. 

M SpexCertiprep mixer mill, vial (2x0.5 inch), ball (0.125 inch), acetylene Pd(Ph3)4 K2C03 1 0.025 1. 

Alkynes undergo stoichiometric oxidative reactions with Pd(II). A useful reaction is oxidative carboiiyiation. Two types of the oxidative carbonyla-tion of alkynes are known. The first is a synthesis of the alkynic carbox-ylates 524 by oxidative carbonylation of terminal alkynes using PdCN and CuCh in the presence of a base[469], Dropwise addition of alkynes is recommended as a preparative-scale procedure of this reation in order to minimize the oxidative dimerization of alkynes as a competitive reaction[470]. Also efficient carbonylation of terminal alkynes using PdCU, CuCI and LiCi under CO-O2 (1 I) was reported[471]. The reaction has been applied to the synthesis of the carbapenem intermediate 525[472], The steroidal acetylenic ester 526 formed by this reaction undergoes the hydroarylalion of the triple bond (see Chapter 4, Section 1) with aryl iodide and formic acid to give the lactone 527(473],... 

Transition-Metal Catalyzed Cyclizations. o-Halogenated anilines and anilides can serve as indole precursors in a group of reactions which are typically cataly2ed by transition metals. Several catalysts have been developed which convert o-haloanilines or anilides to indoles by reaction with acetylenes. An early procedure involved coupling to a copper acetyUde with o-iodoaniline. A more versatile procedure involves palladium catalysis of the reaction of an o-bromo- or o-trifluoromethylsulfonyloxyanihde with a triaLkylstaimylalkyne. The reaction is conducted in two stages, first with a Pd(0) and then a Pd(II) catalyst (29). 

Succinic acid diesters are also obtained by one-step hydrogenation (over Pd on charcoal) and esterification of maleic anhydride dissolved in alcohols (40) carbonylation of acrylates in the presence of alcohols and Co complex catalysts (41—43) carbonylation of ethylene in alcohol in the presence of Pd or Pd—Cu catalysts (44—50) hydroformylation of acetylene with Mo and W complexes in the presence of butanol (51) and a biochemical process from dextrose/com steep Hquor, using Jinaerobiumspirillum succiniciproducens as a bacterium (52). 

The overhead of the depropanizer is sent to the propylene fractionator. The methylacetylene (MA) and propadiene (PD) are usually hydrogenated before entering the tower. An MAPD converter is similar to an acetylene converter, but operates at a lower temperature and in the Hquid phase. Due to recent advances in catalysis, the hydrogenation is performed at low temperatures (50—90°C) in trickle bed reactors (69). Ordy rarely are methylacetylene and propadiene recovered. 

Pd Ultra fine particle Decomposition of metal carbonyl 800 Acetylene 24... 

TABLE XL 3-Alkynylpyrazoles Prepared by Pd/Cu-Catalyzed Couplings between Acetylenes and Pyrazolylhalides [81IZV1342 86TH1 99JCS(P1) 3713]... 

TABLE XIII. Polyalkynylpyrazoles Prepared by Cu- or Pd/Cu-Catalyzed Coupling between Acetylenes and Pyrazolylhalides [71IZV1764 72IZV2524 86TH1 92IZV507]. 

Amines (7a,12a), especially pyridine (75), have also been used as solvents in the hydrogenation of acetylenes. Hydrogenation of 3 over 5% Pd-on-BaS04 in pyridine gave df-cis-jasmanate (4) quantitatively (40). The authors comment that this combination for reduction of acetylenes was superior to the Lindlar catalyst in all cases examined. (See also Refs. 12 and 24 for similar conclusions.)... 

A useful self-terminating catalyst system (77), employs a Pd catalyst [prepared from Pd(OAc)2, NaH, and r-AmOH in THF]. The solvent required for the hydrogenation depends on the acetylene structure monosubslituted acetylenes require solvents such as hexane or octane, whereas disubstituted acetylenes need ethanol, ethanol-hydrocarbon, or ethanol-THF mixtures. In all cases it was necessary to use quinoline as a catalyst modifier. The authors consider this system one of the best for achieving both high yield and stereoselectivity. 

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