Kiyoshi Kikukawa

Reaction of diazonium salts with transition metals—III: Palladium(0)-catalyzed arylation of unsaturated compounds with arenediazoium salts

Abstract Palladium (0) catalyzed reactions of arenediazonium salts for arylation of aliphatic and cyclic olefins and allylic alcohols, styrene and ethyl acrylate were studied. Effects of the olefinic compounds and other reaction variables on the arylation were presented. Arylpalladium species was proposed as the most plausible intermediated in this reaction.

Reaction of diazonium salts with transition metals: IX. Reaction of vinyltrimethylsilane with arenediazonium tetrafluoroborates under palladium(0) catalysis☆

Arenediazonium tetrafluoroborates (ArN2BF4 where ArPh, 4-MeC6H4, 4-BrC6H4, 4-IC6H4 and 4-NO2C6H4) reacted easily with CH2CHSiMe3 at 25 δC to give ArCHCH2, (E-ArCHCHSiMe3 and Ar(Me3Si)CCH2 in excellent yields under palladium(O) catalysis. (E)-ArCHCHSiMe3 compounds were obtained predominantly and isolated in good yields by using an excess of CH2CHSiMe3 over ArN2BF4. Protodesilylation of the reaction mixture afforded styrene derivatives.

Reaction of diazonium salts with transition metals: X. Formylation of arenediazonium salts with carbon monoxide and silyl hydrides under palladium catalysis

Abstract Arenediazonium tetrafluoroborates (ArN 2 BF 4 where Ar = X-C 6 H 4 ; X = H, 2-Me, 3-Me, 4-Me, 4-MeO, 4-MeCO, 4-EtOCO, 2-Ph, 2-Cl, 3-Cl, 4-Cl, 4-Br, 4-I, 3-NO 2 and 4-NO 2 ) were easily converted to aromatic aldehydes (ArCHO) in good yields through the palladium-catalyzed reaction with CO and Et 3 SiH or polymethylhydrosiloxane (PMHS) at room temperature.

Reaction of coordinated phosphines. VI. Divalent palladium promoted cleavage of carbon-phosphorus bonds in tertiary phosphines

Abstract The important role of divalent palladium in the cleavage of carbon—phosphorus bond of tertiary phosphines is revealed by the study of the phenylation in the Pd(OAc) 2 Ph 3 P-styrene system under various conditions; reaction atmosphere, ratio of Ph 3 P/Pd(OAc) 2 , and addition of ethanol or Cu II (OAc) 2 · H 2 O.

Oxidation of isobutene and methylenecycloalkanes by palladium(II) acetate

Abstract Reactions of isobutene, methylenecyclopentane, methylenecyclohexane and methylenecycloheptane with palladium acetate were studied in acetic acid at 30 to 80°. Two types of oxidation were identified: acetoxylation to allylic acetates (methylenecycloheptane) and oxidative coupling to dimers (isobutene and methylenecyclohexane). A mechanistic study indicated that the former was produced by thermal decomposition of the initially formed π-allylic complex. The latter process was presumed to proceed via an insertion of the olefin into the carbonpalladium bond in the acetoxypalladate adduct, followed by the elimination of the elements of acetic acid and palladium hydride.

Reaction of diazonium salts with transition metals. XII. Palladium-catalyzed aryldestannylation of α-styrylstannanes by arenediazonium salts

Abstract Under palladium(0) catalysis, Ph(R 3 Sn)CCH 2 (R = Me, Et and Bu) easily reacted with ArN 2 BF 4 (Ar = XPh, X = H, 4-Me, 4-I, 4-MeCO, 4-EtOCO, 3-NO 2 and 4-NO 2 ) and selectively produced ( Z )-PhCHCHAr but not Ph(Ar)CCH 2 . An addition-elimination mechanism instead of the transmetallation from tin to palladium is postulated for this unusual regiochemistry.

Reaction of diazonium salts with transition metals : V. Cationic aryldiazenido complexes of palladium

Abstract The title complex, [ArN 2 Pd(PPh 3 ) 3 ]PF 6 (Ar = 4-methoxyphenyl), was prepared by the reaction of ArN 2 PF 6 with (PPh 3 ) 4 Pd o . Other ArN 2 X (Ar = phenyl, 4-tolyl, 4-fluorophenyl, 2,4,6-trichlorophenyl; X = BF 4 , PF 6 ) gave a mixture of aryldiazenido and arylpalladium complexes. The aryldiazenido complexes decompose to arylpalladium compounds at room temperature, UV irradiation facilitates this decomposition.

Novel transformation of arenediazonium salts to acid anhydrides under palladium catalysis

Abstract Palladium catalyzed reaction of arenediazonium salts, carbon monoxide and sodium carboxylates gave mixed anhydrides, which in turn could be converted to aromatic acid anhydrides in good yields.

Stereospecific phenylation of alkenylsilanes with phenylpalladium acetate

Abstract (E)- and (Z)-RCH=CHSiMe 3 (R=Ph, n-C 6 H 13 , CH 3 OCH 2 ) reacted stereospecifically with Ph-Pd-OAc to give RCH=C(Ph)SiMe 3 and R(Ph)C=CHSiMe 3 with inversion of the starting geometry with respect to R and Me 3 Si groups.

New applications of crown ethers. Part 8. Complexation of bis(monoazacrown ether)s with alkali-metal cations

The complexation behaviour of bis(monoazacrown ether)s (BCA15C5, BCA18C6, BOA15C5, BOA18C6) with alkali-metal cations was studied by means of solvent extraction, stability constants in homogeneous solution, and 13C n.m.r. spectroscopy. Bis(monoaza-18-crown-6)s, BCA18C6 and BOA18C6, cannot form an intramolecular sandwich complex with K+, probably because of the stability of the macrorings in pseudo-D3d conformation, and also of preferential donation of the oxygen atom in the bridging chain in BOA18C6, as in ‘lariat ethers’. For bis(monoaza-15-crown-5), especially for BOA15C5, the existence of the intramolecular sandwich structure was found both in Na+ and K+ complexes. It is presumed that the more flexible monoaza-15-crown ring does not suffer from restraint in the formation of the sandwich structure, and the oxygen atom in the bridging chain not only increases the flexibility of the chain but also can co-ordinate directly with the cation held in the sandwich cavity.