One‐Pot Sequential Schmidt and Ritter Reactions for the Synthesis of N‐tert‐Butyl Amides

Abstract

The first example of the direct conversion of benzaldehydes into their corresponding N‐tert‐butyl amides through a Schmidt reaction/Ritter reaction sequence is described. A reagent mixture consisting of NaN3 and HBF4·OEt2 in acetic acid efficiently reacts with aromatic and conjugated (α,β‐unsaturated) aldehydes to produce nitrile derivatives, which in situ undergo a Ritter reaction with tert‐butyl acetate to afford the corresponding N‐tert‐butyl amides in almost quantitative yields. The method needs no column chromatography purification. The wide substrate scope as well as the ready availability of the reagent system also make this protocol convenient.

BiCl3 catalyzed synthesis of 2-amino-1,4-naphthoquinones and 1,4-naphthoquinon-2-sulfides and one-pot sequential amine-arylation of 1,4-naphthoquinone

“…Recent publications by different research groups have proved that 2-amino-1,4-naphthoquinones are very good free radical acceptors that participate in several free-radical addition/cascade addition reactions. 15 Given the importance of these derivatives and our efforts toward the development of one-pot synthetic strategies 16 as well as organic transformations via free radicals, 17 we herein wish to report a BiCl 3 catalyzed efficient method for the synthesis of 2-amino-1,4-naphthoquinones and 1,4-naphthoquinon-2-sulfides and a one-pot C3 arylation of 2-amino-1,4-naphthoquinones by using arylhydrazines in the presence of the oxidant K 2 S 2 O 8 (our reports, Scheme 1).…”

Improved Schmidt Conversion of Aldehydes to Nitriles Using Azidotrimethylsilane in 1,1,1,3,3,3-Hexafluoro-2-propanol

“…Similarly, good results can be obtained using a catalyst in an ionic liquid medium [47]. A one-pot sequential Schmidt/Ritter reactions in the presence of 4 equiv of HBF 4 · OEt 2 (2 equiv for each reaction) was also reported for the synthesis of N - tert -butylbenzamides from benzaldehydes [48]. We recently reported an efficient substoichiometric catalytic version of another type of Schmidt reaction, specifically the intramolecular Schmidt reaction of ketones with alkyl azides.…”

Practical Synthesis of N-(Diphenylmethyl)- and N-(1-Adamantyl)amides Directly from Aldehydes via a One-Pot Schmidt and Ritter Reaction Sequence

“…Following the optimal reaction conditions of our earlier report 14 for this sequential reaction, we first attempted the reaction of p-anisaldehyde (1c, 1.0 mmol) with sodium azide (1.5 mmol) using 2.0 equivalents of HBF 4 ·OEt 2 as a promoter in acetic acid at room temperature, followed by the addition of benzhydrol (2, 1.0 mmol) and an additional 2 equivalents of HBF 4 ·OEt 2 . The reaction mixture was allowed to stir at ambient temperature for a stipulated time.…”