Noncovalent Li···H interaction was utilised as a tool for the second lithiation of 4-lithio-1,8-bis(dimethylamino)naphthalene with n-BuLi in the presence of TMEDA in hexane. Metallation proceeds with 100% selectivity in the second peri-position and with up to 90% yield. A series of 4,5-disubstituted derivatives of 1,8-bis(dimethylamino)naphthalene has been prepared in good to excellent yield after quenching the reaction mass with different electrophiles.
The bromine-lithium exchange sequence upon interaction of 2,4,5,7-tetrabromo-1,8-bis(dimethylamino)naphthalene with n-BuLi was studied. Experimental results were explained by means of quantum chemical calculations. It was demonstrated that the first exchange occurs in position 4 due to the significant decrease of a steric strain of the molecule. The second exchange takes place in either position 5 or 7 due to the even more negative charge distribution in the naphthalene core. As a result, the third exchange leads to the species containing lithium in positions 2,4,5 or 2,4,7. Using a large excess of n-BuLi in hexane, 2,4,5,7-tetralithio-1,8-bis(dimethylamino)naphthalene was successfully prepared. The latter was used for the synthesis of several tetrasubstituted derivatives of 1,8-bis(dimethylamino)naphthalene by quenching with different electrophiles.
Triphenylpnictogens were oxidazed to access diphenylpnictiogenic acids Ph2XOOH (X = P, As, Sb, Bi). It was shown that oxidation with chloramine-T does not lead to the cleavage of a C–pnictogen...
A series of ortho-, meta-, and para-boronic acids and their pinacol esters of 1,8-bis(dimethylamino)naphthalene (DMAN), including the very first naphtho[1,8-cd][1,2,6]oxadiborinine-based proton sponge, were synthesized with moderate to good yields. The ease of deborylation of sterically hindered ortho-boronic acids of DMAN was demonstrated. DMAN-based 3,6-diboronic acid and its pinacol ester valuable precursors for meta-derivatives of the naphthalene proton spongewere prepared and utilized for the synthesis of 3,6-diiodo-DMAN. Obtained acids and esters were tested for common palladium and copper catalyzed couplings.
The interaction of peri-dilithionaphthalenes with
organic cyanides was studied. Instead of the expected peri-diimines, the reaction leads to the formation of three types of
benzo[de]isoquinolines. Treatment of unsubstituted
1,8-dilithionaphthalene with aromatic nitriles results in the formation
of 1-amino-1,3-diaryl-1H-benzo[de]isoquinolines. In contrast, 4,5-dilithio-1,8-bis(dimethylamino)naphthalene
gives an aromatic isoquinolonium cation via elimination of ammonia
under the same condition. Upon treatment with tert-butylcyanide, both dilithionaphthalenes undergo a transformation
to 1-amino-3,4-di-tert-butyl-4H-benzo[de]isoquinolines. The observed reactivity was supported
by quantum chemical calculations.
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