Benzyl derivatives carbon-nitrogen bonds

Naphthalene-catalyzed lithiation of l,3-dimethyl-2-phenylimidazolidine leads to cleavage of the benzylic carbon-nitrogen bond, with formation of an intermediate dianion. The dianion could be trapped with several electrophiles, including primary and secondary alkyl halides, as well as enolizable and nonenolizable carbonyl derivatives, affording diamines 485 in satisfactory yields (Scheme 112) <2005T3177>. 

Topics that have formed the subjects of reviews this year include contemporary issues in electron transport research, dynamics of bimolecular photoelectron transfer reactions, photophysical properties of functionalised fullerene derivatives, carbon-carbon bond formation via radical ions, photoinduced electron transfer processes in ketone, aldehyde, and ester synthesis, photochemical reactions between arenenitriles and benzylic donors, photo-oxidation of conjugated dienes, photoredox reactions of aromatic nitro compounds, electron transfer-mediated photochemistry of some unsaturated nitrogen-containing compounds, reactions of 02( Ag), carbon dioxide activation by aza-macrocyclic complexes, and photochromism of chalcone derivatives. ... 

Activation of C=N Double Bonds. TBDMS triflate has been used to promote additions to, and for the isomerization of, a number of systems containing carbon-nitrogen double bonds. TBDMS triflate is the optimal silyl triflate to promote the Mukaiyama-type vinylogous imino-aldol (Mannich-type) addition of 2-[(f-butyldimethylsilyl)oxy]furan to the IV-benzyl imine derived from (25)-2,3-0-isopropylideneglyceraldehyde (eq 36). ... 

The reactive zwitterions arising from the nucleophilic attack of imines 479 on the benzyne generated in situ from 2-(trimethylsilyl)phenyl triflate 478 proved to be an appropriate molecular scaffold for the capture of CO2 with sufficient electrophilicity to yield 2-aryl-3,l-benzoxazin+-ones 480 (Equation 53). Both substituents of the C=N bond affected the course of the reaction considerably the best yields were achieved by using imines with electron-rich or neutral aryl groups on the carbon, and benzyl or nonbranched chain alkyl substituents on the nitrogen atom. With substituted derivatives of 478, the unsymmetrically substituted arynes led to regioisomeric products <2006JA9308>. 

Arylpyrroles, substituted or unsubstituted at the nitrogen, undergo a much more drastic oxidation than alkyl derivatives by the action of hydrogen peroxide. In most cases opening of the heterocyclic ring occurs, both at the bond between the heteroatom and the a-carbon and between the a- and )8-carbon atoms. From 2,5-diphenylpyrrole in acetic medium benzoic acid and acetophenone are formed.51 From 2,3,5-triphenyl-pyrrole (58, R = H) the product is 59,61 while from 58 (R = benzyl) the compounds 60 (R = benzyl) and 61 are produced.62 Other pyrroles that were found to behave similarly are listed below. 

For the preparation of 2-aminobenzimidazole (206), it is first necessary to substitute the proton in the 1-position with a protecting group. Such groups can be benzyl, alkyl-substituted benzyls, or benzhydryl, which derivatives aminate with sodium amide in DMA. The nitrogen-carbon bond can then be cleaved by sodium in liquid ammonia to give 206 (Scheme 73) (72CHE731). 

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