Pyridine Al-oxides

The force constants obtained for sulphoxides and sulphones are about 7 x 10 and 10 X 10 dyne cm respectively The values of the force constants for sulphoxides are very similar to those of the N—O bond in pyridine Al-oxides in which the k values are approximately 6-7 x 10 dynecm ... 

AmUnotetruhydrofurans The complexes derived from Cp Zr and 1 -aza-1,3-dienes insert carbonyl compounds which on demetallation with pyridine Al-oxide lead to 2-anilinotetrahydrofurans, and thence to the y-lactols and other compounds. 

In contrast, the reaction of pyridine Al-oxide, or its 3-methyl or 4-methyl derivative) with phosgene in dichloromethane, in the absence of added base, gives hydrolytically unstable carbonate salts [811aa] ... 

Kiplinger and co-workers have also demonstrated dearomatization of pyridines with metals <05CC2591>. In the case reported, thorium complexes mediated ring opening and dearomatization of pyridine Al-oxides yielding the thorium oximate complexes. 

Some S -bonded DMSO iron(II) complexes are known, but the explosive pale green complex [Fe(DMSO)6](C104)2 formed when the hexaqua perchlorate is mixed with dimethylsulfoxide in acetone, appears to be O-bonded. Hexaaqua iron (II) reacts with pyridine Al-oxide to give dark red [Fe(pyO)6] , and analogous complexes are formed with a variety of substituted pyridine Al-oxides. 

Zinc Derivatives. 2-(Benzopyran-4-yl)pyridine Al-oxide has been prepared from 2-chlorozinciopyridine 7V-oxide and benzopyran-4-yl triflate in a Negishi-type coupling from 2-chlorozinciopyridine N-oxide (Scheme 66). A five-fold excess of the the zincated pyridine A-oxide had to be used for optimal formation of the cross-coupled product 161. 

Scheme 5 Arylation of pyridine Al-oxides using aryl triflates...

Synthesis of 2-substituted pyridines from pyridine Al-oxides 13ARK (1)154. 

The reaction of pyridine Al-oxides with dichloroketene affords a mixture of the [3+2] cycloadduct 365 and the bicyclic lactone 366 . ... 

A sterically and electronically diverse collection of live- and six-membered lactams and cyclamines could be employed, including piperidine, pyrrolidine, morpholine, piperizine, and 2-oxazolinone. Pyridine Al-oxide was unreactive. 

Palladium-catalyzed Direct Arylation of Pyridine N-Oxides, Pyrazine N-Oxides, Pyridazine N-Oxides, Pyrimidine N-Oxides, and Thiazole N-Oxides. Pyridine W-oxides can be efficiently ary-lated at the C2 position using aryl halides as the electrophile, palladium acetate as the catalyst, tri-tert-butylphosphonium tetraflu-oroborate as the ligand, and potassium carbonate as the base (eq 19). In this protocol, 3 equiv of pyridine Al-oxide are utilized to generate the corresponding 2-aryl derivatives. ... 

Masaguer, I.R., Sousa-Alonso, A., Sueiras, J. and Garcia Vazquez, J.A. (1977) Charge-transfer complexes of iodine monobromide with methyl derivatives of pyridine Al-oxide. An. Quim., 73, 384-390. 

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