N-tert-Butoxycarbonyl azide (BocN 3 ) was shown to be an efficient and economic source for the directed introduction of N-Boc protected amino groups into the thiophene and benzene nucleus. Yields for the amination of 2-pyridin-2-ylthiophenes (10 examples) were 52-88%. For the amination of the respective benzenes (10 examples) yields between 54% and 99% were recorded with an improved reactivity observed for substrates that bear an electron-withdrawing group. The reaction was applied to short total syntheses of the indoloquinoline alkaloids quindoline and cryptolepine. The facile removal of the Boc protecting group was the key to the success of the syntheses. The scope of the reaction was extended to a C(sp 3 ) À H bond amination and to the amination of 2-phenyloxazoline. For the amination of 2-pyridin-2-ylbenzene a kinetic deuterium isotope effect of 2.0 was determined.
N‐tert‐Butoxycarbonyl azide (BocN3) was shown to be an efficient and economic source for the directed introduction of N‐Boc protected amino groups into the thiophene and benzene nucleus. Yields for the amination of 2‐pyridin‐2‐ylthiophenes (10 examples) were 52–88%. For the amination of the respective benzenes (10 examples) yields between 54% and 99% were recorded with an improved reactivity observed for substrates that bear an electron‐withdrawing group. The reaction was applied to short total syntheses of the indoloquinoline alkaloids quindoline and cryptolepine. The facile removal of the Boc protecting group was the key to the success of the syntheses. The scope of the reaction was extended to a C(sp3)H bond amination and to the amination of 2‐phenyloxazoline. For the amination of 2‐pyridin‐2‐ylbenzene a kinetic deuterium isotope effect of 2.0 was determined.
The oxidative cross-coupling of phenols (3 equiv) to various substituted phenyl N,N-diethylcarbamates was explored with a variety of substrates. Pd(OAc)2 was employed as the catalyst (20 mol%) and K2S2O8 as the stoichiometric oxidant in trifluoroacetic acid as the solvent (50 °C, 2 h). Carbamates without or with a substituent on the phenyl ring (Me, Ph, Cl, OMe) underwent the reaction unless the phenyl substituent was too strongly electron withdrawing (CN). Cross-coupling occurred exclusively in the ortho position relative to the carbamate group. The regioselectivity at the phenol (ortho or para to hydroxy) was mainly determined by steric factors. Yields up to 60–70% were achieved for specific carbamate/phenol combinations.
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