The “Thermal” Rearrangement of Hydrazo Compounds. III.¹ The Kinetics and Mechanism of the Rearrangement of 2,2'-Hydrazonaphthalene in Polar Solvents

Mechanism for the reaction of 2‐naphthol with N‐methyl‐N‐phenyl‐hydrazine suggested by the density functional theory investigations

“…The imaginary frequency of 299.37 icm À1 is mainly associated with the coupling of the formation of C1AC6 bond and the rupture of N1AN2 bond, which further manifests Shine's ' 'concerted' ' rearrangement mechanism as stated in the Introduction section. [32,43] In the sequential process, the diimino compound is stabilized via two water-assisted proton migrations to offer the final product. The transition state 3_TS3 is a six-membered ring structure.…”

“…[29][30][31] The mechanism and kinetics of rearrangement of hydrazo compounds were intensively studied in the mid 1900s. [32][33][34][35][36][37][38][39][40][41][42][43] In 1960, Shine and Trisler examined the influence of solvent on the rearrangement of 2,2 0 -hydrazonaphthalene and reported two rearrangement products 2,2 0 -diamino-l,1 0 -binaphthyl and carbazole, first proposing a ' 'concerted' ' rearrangement idea that carbon-carbon bond making occurs while the nitrogen-nitrogen bond is breaking. [32] Later, Shine's group investigated the detailed mechanism of the benzidine rearrangement and further explained the concerted rearrangement by three major theories involving the rate-determining ring protonation, the polar transition-state theory, and the p-complex theory.…”

Rearrangements of Hydrazo, Azoxy and Azo Compounds: Kinetic, Product and Isotope Studies

“…In all cases labelled azobenzenes were prepared first, recrystallized with appropriate amounts of unlabelled azobenzenes if necessary 10 and then reduced to hydrazobenzenes with zinc and NH 4 Cl in aqueous SCHEME 1 acetone 11 , so only the azobenzene syntheses are described below. In most cases the azobenzene was prepared from the appropriately labelled aniline by oxidizing it with MnO 2 12 .…”

“…[1-14 C]azobenzene and [1, 1 -13 C 2 ]azobenzene 8 were prepared from[2-14 C]acetone and[2-13 C]acetone, respectively, by converting them to[1-14 C]-and [1-13 C]-4-nitrophenol14 , the corresponding anilines being derived from these as described8 . [2, 2 , 4, 4 -13 C 4 ]azobenzene was obtained from the [2,6-13 C 2 ]aniline that could be prepared from[1,[3][4][5][6][7][8][9][10][11][12][13] C 2 ]acetone 15 . removing the NH 2 , reducing, acetylating, para-chlorinating and deprotecting, giving [2-14 C]-4-chloroaniline; condensation of this with unlabelled 4-chloroaniline gave the required product 16 .…”

Regiospecific Synthesis of Novel Cyclic Nitrostyrenes and 3-Substituted 2-Nitronaphthalenes

“…The first scalable organocatalytic atroposelective synthesis of BINAM derivatives was recently demonstrated in our laboratory utilizing a remarkably efficient [3,3]-sigmatropic rearrangement of binaphthyl hydrazines in the presence of 5-20 mol% chiral acid catalysts (Scheme 1). 1 The required binaphthyl hydrazine substrates were prepared from the corresponding substituted 2-naphthylamines via a three-step procedure 2 that involved: (a) diazotization, (b) reduction of the diazonium salt to the corresponding symmetrical azo compound, and (c) reduction of the azo group with Zn/NH 4 Cl. However, a convenient and readily scalable synthetic access to a wide variety of substituted 2-naphthylamines, especially to 3alkyl-and 3-aryl-2-naphthylamines, remains a significant challenge.…”