摘要:

AbstractThe photooxidations of γ‐hydroxysulfides which give abnormally high yields of sulfones have been investigated. This unusual result is attributed to the potent trapping ability of a hydrogen bonded sulfoxide intermediate. This suggestion is supported by measuring the ability of a γ‐hydroxysulfoxide to trap the persulfoxide formed in the photooxidation of diethyl sulfide and by careful analysis of the reaction composition as a function of

ISSN:1042-7163    

DOI:10.1002/hc.520040213

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe fluoride ion‐induced rearrangement of Ph(ClCH2)SiH2was expected to provide either PhMeSiHF (migration of hydride) or (PhCH2)SiH2F (migration of phenyl). However, when Bu4N+F−(commercial TBAF) is added to Ph(ClCH2)SiH2, a mixture of fluorine‐terminated siloxanes, FPhMeSiO(PhMeSiO)xSiMePhF, is obtained. The presence of the Me group suggests a rapid anion‐induced migration of hydride to produce PhMeSiHF which reacts further with water present in TBAF samples. When the reaction mixture is cooled to 0°C or is monitored at the early stage of the reaction, the major products are PhMeSiF2, PhMeSi(OH)F, PhMeSi(OH)2, and FPhMeSiOSiMePhF which are proposed as the building blocks for the siloxanes. When dried CsF in CH3CN is used, the major products are PhMeSiF2and PhMeSiH2which are assumed to form from the fluoride ion‐induced disproportionation of PhMeSiHF. The reaction chemistry is rationalized in terms of hypervalent intermediates. The fluoride ion‐induced reactions of PhMeSiH2and PhMeSiCl2are also described and compared to those of P

ISSN:1042-7163    

DOI:10.1002/hc.520040214

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe preparation of 1,1‐difluoro‐3,7‐di‐tert‐butyl‐2,8‐dioxa‐1‐phosphabicyclo[3.3.0]octa‐3,6‐diene (Dit‐BuADPO·F2)from hexafluoropropylene oxide (HFPO) and 3,7‐di‐tert‐butyl‐2,8‐dioxa‐1‐phosphabicyclo[3.3.0]octa‐2,4,6‐triene (DitBuADPO) is described. The solid state structure of DitBuADPO·F2shows an unusual square pyramidal geometry. The structural and spectroscopic properties of DitBuADPO·F2are compared with other oxidized derivatives of Di

ISSN:1042-7163    

DOI:10.1002/hc.520040215

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractBoth cyclic and acyclic sulfinate esters were labeled with18O at the sulfinyl oxygen by acid‐catalyzed isotope exchange with H218O or alkaline hydrolysis in H218O followed by re‐esterification. Long‐range18O isotope effects on the13C NMR chemical shifts were obs

ISSN:1042-7163    

DOI:10.1002/hc.520040216

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe reactions of TeCl4with 1 or 2 equivalents of enol silyl ethers yielded trichloro(2‐oxoalkyl)telluriums or dichlorobis(2‐oxoalkyl)telluriums, respectively, in high yields. Stepwise addition of two different enol silyl ethers to TeCl4in CH2Cl2led to the selective formation of unsymmetrical dichlorobis(2‐oxoalkyl)tellu

ISSN:1042-7163    

DOI:10.1002/hc.520040217

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractTriphenylborane (7) undergoes reductive dimerization with sodium metal in diethyl ether solution to form a yellow solid (3) having the empirical composition Ph3B· Na· (C2H5)2O. By1H NMR spectroscopy,3has now been shown to have the structure depicted. By theaction of heat or strongly donor ethers,3rearranges into6, whose structure was likewise determined by1H and11B NMR spectroscopy and by deuteriodeboronation with DOAc. Prolonged reaction of sodium metal with7or with diphenylboron chloride (8) in DME leads to biphenyl precursors, sodium tetraphenylborate (9), and sodium phenylborohydrides. All these results can be reconciled by the formation of the radical–anion10from7and its subsequent coupling or fragmentation. The coupling of10to form3and the rearrangement of3to yield6shows that there is a striking parallel in behavior between the isoelectronic (Ph3B·)−and the triphenylmethyl radical (Ph3C·). In this light, the solution of the “hexaphenylethane riddle” is also applicable to the solution of the “hexaphenyldiborate dianion riddle,” which was posed by the discovery of Krause's adduct ov

ISSN:1042-7163    

DOI:10.1002/hc.520040218

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

Abstract4,6‐Disubstituted thianthrene‐5‐oxides reacted with n‐butyllithium to afford sterically crowded 1,9‐disubstituted dibenzothiophenes(3)in moderate yields. The structures of the phenylthio derivative3aand its monooxide6awere determined by X‐ray crystallographic analysis, which revealed that the distances between the two outer sulfur atoms are 3.012 Å(3a)and 3.016 Å(6a). 1,9‐Disubstituted dibenzothiophenes3and their monooxides6afforded the corresponding dithia dications on dissolution in conc. sulfuric acid. The lower oxidation potentials of compounds3compared with other dibenzothiophene derivatives reveal evidence for strong transannular interaction between the two out

ISSN:1042-7163    

DOI:10.1002/hc.520040219

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractSeveral strategies for the synthesis of α‐trifluoromethyl substituted α‐aminoacids and α‐hydroxyacids with organometallic moieties in the side chain are described. The preparative potential of organometallic substituents (organosilicon, organotin, and organocobalt moieties) offers a convenient methodology for the synthesis of highly functionalized α‐aminoacid and α‐hydroxyac

ISSN:1042-7163    

DOI:10.1002/hc.520040220

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractArenesulfonic acids were found to react with dinitrogen tetraoxide at −40°C in tetrahydrofuran to form arenesulfonyl nitrites which showed excellent diazotizing ability for the reductive deaminations of arylamines to arenes in the presence of anhydrous copper(II) halides as catalys

ISSN:1042-7163    

DOI:10.1002/hc.520040221

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractTreatment of the hydrochloride salts of 4‐chloro‐5‐(2‐halomethylaryl‐imino)‐5H‐1,2,3‐dithiazoles (2) with sodium cyanoborohydride in THF at room temperature gave 2‐cyano‐4H‐3,1‐benzothiazines (1) in good to moderate yields. 2‐Cyano‐4H‐3,1‐benzoxazines (4) were obtained in good to moderate yields by refluxing of 4‐chloro‐5‐(2‐hydroxymethylarylimino)‐5H‐1,2,3‐dithiazoles (3) with sodium hydride in THF. Intermolecular reaction of 5‐(p‐tolylimino)‐5H‐1,2,3‐dithiazole (12) with benzyl alcoho

ISSN:1042-7163    

DOI:10.1002/hc.520040222

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY