(Tosylimino)phenyl-λ³-iodane as a Reagent for the Synthesis of Methyl Carbamates via Hofmann Rearrangement of Aromatic and Aliphatic Carboxamides

Abstract

A new, mild procedure for the Hofmann rearrangement of aromatic and aliphatic carboxamides using (tosylimino)phenyl-λ(3)-iodane, PhINTs, as a reagent is reported. Because of the mild reaction conditions, this method is particularly useful for the Hofmann rearrangement of substituted benzamides, which usually afford complex reaction mixtures with other hypervalent iodine oxidants. The mild reaction conditions and high selectivity in the reaction of carboxamides with PhINTs allow the isolation of the initially formed labile isocyanates or their subsequent conversion to stable carbamates by treatment with alcohols.

The crystal structure of methyl N-(4-bromophenyl)carbamate, C8H8BrNO2

“…We expected to receive 1-cyanoacetylo-4-(4-bromophenyl)semicarbazide in the reaction of cyanoacetic acid hydrazide, 4-bromophenyl isocyanate and methanol according to the literature data [6], but during the reaction methyl N-(4-bromophenyl)carbamate was obtained. We suppose that instead of the isocyanate reaction with the hydrazide, the isocyanate reacted with the methanol, which was the reaction medium giving the title compound.…”

A Regio‐ and Stereodivergent Synthesis of Homoallylic Amines by a One‐Pot Cooperative‐Catalysis‐Based Allylic Alkylation/Hofmann Rearrangement Strategy

“…[24,25] In the presence of methanol, av ariety of oxidants effectively mediated the Hofmann rearrangement of (R)-2-(4-methoxyphenyl)pent-4enamide A,g iving the corresponding methyl carbamate protected homoallylic amine (Table 1). [24,25] In the presence of methanol, av ariety of oxidants effectively mediated the Hofmann rearrangement of (R)-2-(4-methoxyphenyl)pent-4enamide A,g iving the corresponding methyl carbamate protected homoallylic amine (Table 1).…”

Rearrangements Induced by Hypervalent Iodine

“…(Tosylimino)phenyl-λ 3 -iodane, another iodine(III)-based reagent, also facilitates the conversion of a large variety of amides such as 16 into the corresponding isocyanates 17, which are suitable precursors for the synthesis of methyl carbamates 18 as shown in Scheme 6 [6]. The reaction proceeds in very good yields with a variety of electron-rich and electron-poor aryl-substituted amides as well as bulky alkyl-substituted amides.…”