Alcohols tetrakis palladium

In 1988, Linstrumelle and Huynh used an all-palladium route to construct PAM 4 [21]. Reaction of 1,2-dibromobenzene with 2-methyl-3-butyn-2-ol in triethylamine at 60 °C afforded the monosubstituted product in 63 % yield along with 3% of the disubstituted material (Scheme 6). Alcohol 15 was then treated with aqueous sodium hydroxide and tetrakis(triphenylphosphine)palladium-copper(I) iodide catalysts under phase-transfer conditions, generating the terminal phenylacetylene in situ, which cyclotrimerized in 36% yield. Although there was no mention of the formation of higher cyclooligomers, it is likely that this reaction did produce these larger species, as is typically seen in Stephens-Castro coupling reactions [22]. 

Tetraisopropyl titanate Isopropyl alcohol, titanium (4+) salt, 2-Propanol, titanium (4+) salt (546-68-9), 65, 230 Tetrakis(acetonitrile)palladium tetrafluoroborate, (21797-13-7),... 

Tetrakis(triphenylphosphine)-palladium(O), 289 Tin(IV) chloride, 300 Trimethylamine N-oxide, 325 Zinc amalgam, 347 Homoallylic alcohols By addition reactions of allyl to carbonyl groups... 

HOMOALLYLIC ALCOHOLS Cerium amalgam. Chromium(II) chloride. Fluorodimethoxyborane. Hypochlorous acid. Lithium bronze. Manganesc(II) chloride-Lithium aluminum hydride. Methylenetriphenylphosphorane. Organotitanium reagents. Tetrakis(triphenylphosphine)palladium. Tin. Tin(II) fluoride. 

The Step 3 product (14.5 mmol) dissolved in 75 ml of ethyl alcohol was added to a mixture of 4-bromobenzaldehyde (14.5 mmol) and tetrakis(triphenylphosphine) palladium (0.40 mmol) dissolved in 75 ml of toluene, then stirred 15 minutes at ambient temperature. The mixture was further treated with 16.9 ml 2M Cs2C03 solution, then refluxed 3 hours, and concentrated. The residue was dissolved in EtOAc, then washed with water, dried with Na2S04, and reconcentrated. The residue was then purified by chromatography with silica gel using EtOAc/n-heptane, 1 4, and 5.46 g of product isolated as a slightly yellow-colored solid, mp = 140—143°C. 

Reduction of acid chlorides to aldehydes One of the most useful synthetic transformations in organic synthesis is the conversion of an acid chloride to the corresponding aldehyde without over-reduction to the alcohol. Until recently, this type of selective reduction was difficult to accomplish and was most frequently effected by catalytic hydrogenation (the Rosenmund reduction section 6.4.1). However, in the past few years, several novel reducing agents have been developed to accomplish the desired transformation. Among the reagents that are available for the partial reduction of acyl chlorides to aldehydes are bis(triphenylphosphine)cuprous borohydride , sodium or lithium tri-terf-butoxyaluminium hydride, complex copper cyanotrihydridoborate salts °, anionic iron carbonyl complexes and tri-n-butyltin hydride in the presence of tetrakis(triphenylphosphine)palladium(0). ... 

Methylenecyclopentanes. 2-Acetoxymethyl-3-allyltrimethylsilane (1) adds to a variety of electron-deficient alkenes in the presence of catalytic amounts of tetrakis(triphenylphosphine)palladium(0) and l,2-bis(diphenylphosphino)ethane to afford methylenecyclopentanes. The allylsilane 1 is prepared in four steps from methallyl alcohol. 

To a stiiTed solution of ( )-l-iodo-heptene-l (224 mg, 1 mmol) and tetrakis(triphenylphosphine)palladium (58 mg, 0.05 mmol) in pyrrolidine (1.5 mL), under an argon atmosphere, was added a solution of 3-butyn-l-oI (140 rag, 2 mmol) in pyrrolidine (1.5 mL). After being stirred at room temperature for 15 min, the mixture was hydrolyzed with a saturated aqueous solution of ammonium chloride and extracted with diethy ether. The organic extract was dried over MgS04, and the solvent was removed in vacuo. Filtration through silica gel (elution petroleum ether ethyl/acetate,6 4) gave 155 mg (93%) of the pure alcohol 87. 

Treatment of o-dibromobenzene with propargyl alcohol in the presence of tetrakis-(triphenylphosphine)palladium(O) yielded the bromo alcohol 667, which condensed with a second molecule of propargyl alcohol to give the diyne668. The dimethanesulphonate of the latter was added to propylamine over a period of 20-30 hours to afford the 18-membered nitrogen heterocycle 669. ... 

Chiral allylic cyclic carbonates such as 551 or 552 undergo excellent regioselective alkylation reactions with soft nucleophiles in the presence of palladium(O) in refluxing THF to provide ( )-allylic alcohols. The reaction of 4-0-benzyl-2,3-isopropylidene-L-threose (167) with the appropriate ylid, followed by deprotection of the isopropylidene ring with acidic resin and cyclic carbonate formation, provides a good overall yield of either 551 or 552. Ring opening with diethyl malonate in the presence of tetrakis(triphenylphosphine)palladium(0) provides in excellent yield the allylic alcohols 553 or 554, where the diastereoselectivity exceeds 99%. This reaction represents an efficient method of 1,3-chirality transfer [180] (Scheme 122). 

A variety of a-nitroepoxides undergo conversion to the corresponding 1,2-diketones or, in some cases, a-nitroketones with tetrakis(triphenylphosphine)palladium(0) (Scheme [io],[ii] Proposed reaction mechanism is shown in Scheme 16. 2,3-Epoxy alcohols also undergo the Pd(0)-catalyzed reaction to be isomerized to a- or /3-hydroxy ketones or both, depending on the nature of the substituents on the phenyl ring (Scheme... 

TMS-alkynes are oxidized at the terminal carbon to carboxylic acids by hydroboration/oxidation (dicyclohexylborane/NaOH, H2O2). This does not work with TIPS-alkynes. Instead, TIPS-alkynes are cleanly monohydroborated at the internal carbon by 9-borabicyclo[3.3.1]nonane dimer to give (Z)- -borylvinyl-silanes. These can be oxidized in high yields to a-silyl ketones, or cross coupled with a bromide R Br (R = aryl, benzyl, dimethyl-vinyl) in the presence of NaOH and tetrakis(triphenylphos-phine)palladium(0) to give /3,/3-disubstituted vinylsilanes (Suzuki reaction eq 14). The same nucleophilic substituted vinylsilane can be added to an aromatic aldehyde to provide access to ( )-3-silyl allyl alcohols. ... 

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