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Organometallic Tetrazole Derivatives: Preparation and Application to Organic Synthesis

“…The reaction with tetrazole carried out in dichloromethane in the presence of boron trifluoride etherate gives rise to a compound that is difficultly assignable to 1-or 2-isomer. 5-Phenyltetrazole under these conditions furnished a mixture of the corresponding disubstituted tetrazoles with 2,5-isomer prevailing [90]. Quite a number of these compounds was recently described where M = Al [91], Mn [92], Fe [93], Mo [94], Ru [95,96], Rh [97], Pd [31], Hg [98], Tl [99], Sn [100 -108].…”

ortho-effect of hexacarbonyldicobaltacetylene substituents of propargyl type in aromatic systems

“…The unsubstituted 1H-tetrazole gives one N-cobaltpropargylated product, whose assignment to the N 1 -or N 2 -substitution is impossible. However, N,N-bis(μ,η 2 -hexacarbonyldicobalt-2-propynyl)carbamide was detected as a byproduct [3]. Its formation can be represented as the result of biscobaltpropargylation of tetrazole on the N 1 -and N 4 -positions, followed by the oxidative degradation of the ring, which loses aromaticity due to the introduc-tion of the second cobaltpropargyl moiety into the ring.…”

“…The progenitor compound, pyrrole, is cobalt-propargylated with this complex on the α-carbon atom to form 2-(μ,η 2 -hexacarbonyldicobalt-2-propynyl)pyrrole [3]. An attempt to introduce the second hexacarbonyldicobalt moiety into HNposition failed, although the cationic character of the reagent formed in the presence of BF 3 .…”

“…The C-substituted tetrazoles are cobaltpropargylated at the nitrogen atoms N 1 or N 2 to form primarily the N 2 -monosubstituted products [3]. The unsubstituted 1H-tetrazole gives one N-cobaltpropargylated product, whose assignment to the N 1 -or N 2 -substitution is impossible.…”

“…The latter generates in situ a superstable carbenium cation Co 2 (CO) 6 (R)C≡CC + (R 2 ), where R are hydrogen atoms or different organic substituents. Such cations are sufficiently active electrophilic reagents [1][2][3].…”