An Unexpected [1,5]-H Shift in the Synthesis of Nitroanilines

Abstract

Addition of methyl acetoacetate to 2-nitrovinamidinium hexafluorophosphate salts leads to the formation of anilines or phenols in good to excellent yields depending on the alkylamine substituents. Small substituents, e.g., pyrrolidine, lead to the formation of anilines while large substituents, e.g., N,N-diisopropyl, exclusively give phenols. Labeling studies implicate a [1,5]-H shift proceeding with excellent isotopic fidelity.

A [2 + 2] Cycloaddition Route to Dimethylaminomethylene Vinamidinium Salts

“…6 On the basis of the ease of access to these interesting synthons, we have continued to explore the synthetic utility of a range of vinamidinium hexafluorophosphate salts for heterocycle synthesis 7 and more recently in the synthesis of anilines. 8 In this Letter, we disclose a unique transformation that is able to deliver the exceptionally thermally stable dimethy- laminomethylene hexafluorophosphate salts 9 from β-fluoroalkanoic acids. Spectroscopic studies are used to define the reaction pathway, which allows us to construct a mechanistic framework involving two cycloaddition processes.…”

“…On the basis of the ease of access to these interesting synthons, we have continued to explore the synthetic utility of a range of vinamidinium hexafluorophosphate salts for heterocycle synthesis and more recently in the synthesis of anilines …”

Synthetic application of fluorinated vinamidinium salts: Synthesis of fluorinated 1,3-butadienylphosphonates by the reaction with Horner–Wadsworth–Emmons reagents

“…Therefore, much efforts have been made to prepare many kinds of vinamidinium salts having various substituents and to apply them in organic synthesis [1][2][3][4]. Recently, the Merck research group has actively investigated the preparation of a variety of vinamidinium salts and successfully applied them to the synthesis of a highly potent, specific COX-2 inhibitor [5][6][7][8][9]. Although the availability of fluorine-containing vinamidinium salts should open new routes to various kinds of fluorinated compounds of biological and materials science interest, there were few reports on fluorinated vinamidinium salts [10][11][12] prior to our research concerning this area.…”

Computational Studies on the Electrocyclizations of 1-Amino-1,3,5-hexatrienes

“…However, we have demonstrated that ring closure to provide aromatic products occurs in the case of nitro-, phenylsulfonyl-, and dimethylaminomethylene substitution. 6,7 The major reaction pathway has been formalized as (1) enamine or enol formation, (2) electrocyclization, and (3) elimination of dimethylamine to provide the aromatic product (Scheme 1). 8 The electrocyclization of 1,3,5-hexatrienes having a 1-dimethylamino latent leaving group has been previously observed 9 and similarly occurs for the 1-SMe 10 and 1-Cl 11 hexatrienes.…”