Synthesis of 2,4-disubstituted thiophenols and solid state structures of thiocarbamate precursors

Abstract

quais mostram diferentes graus de impedimento estérico na posição 2, foram preparados a partir dos correspondentes fenóis. Uma despronotação inicial dos fenóis foi obtida com o uso de NaH em dimetoxietano, seguido de tratamento com cloreto de N,N-dimetiltiocarbomoila, obtendo-se os O-ariltiocarbamatos. A termólise destes compostos resultou num rearranjo, obtendo-se os S-ariltiocarbamatos. Finalmente, a redução dos Sariltiocarbamatos com LiAlH 4 em THF, seguido de acidificação, levou ao isolamento dos tiofenóis. Todos os produtos foram caracterizados por técnicas espectroscópicas, e para alguns tiocarbamatos a estrutura sólida foi determinada por difração de raio X.A series of thiophenols with different ortho-substituents, 2,4-dimethylthiophenol, 2-tert-butyl-4-methylthiophenol, and 2-(1-adamantyl)-4-methylthiophenol, which display varying degrees of steric hindrance on the 2-position, was prepared from the corresponding phenols. Initial deprotonation of the phenols was achieved with NaH in dimethoxyethane, followed by treatment with N,Ndimethylthiocarbamoyl chloride, to obtain the O-arylthiocarbamates. Thermolysis of the latter compounds resulted in rearrangement, which yields the desired S-arylthiocarbamates. Finally, reduction of the S-arylthiocarbamates with LiAlH 4 in THF, followed by acidic workup, allowed the isolation of the thiophenols. All products were characterized by spectroscopic techniques, and in the case of some of the thiocarbamates the solid state structures were determined by single-crystal X-ray diffraction.

Silver Complex of an N-Heterocyclic Carbene Ligand with Bulky Thiocarbamate Groups

“…Selected bond distances include those of the imidazole ring, N1-C3 1.346(10) and N2-C3 1.331(9) Å, with an N2-C3-N1 angle of 107.8(7)°; the former N-C distance would correspond to the formally single bond, and thus N2 would have to be considered as cationic. The metric parameters of the thiocarbamate moieties are similar to those reported for related compounds, 26,27 including S1-C20 and S2-C39 of the thiocarbamate groups at 1.820(9) and 1.814(8) Å, respectively; the corresponding carbonyl O1-C20 and O2-C39 distances of 1.113(18) and 1.221(9) Å are also similar to those observed for related systems. Complete metric parameters are presented in Table S4 (SI section).…”

S-2-(Adamant-1-yl)-4-methylphenylN,N-dimethylthiocarbamate

“…position of phenols represents a synthetic challenge in this methodology, and the experimental difficulties have been attributed by our group to the steric congestion around the thiocarbamate moiety (Flores-Figueroa et al, 2005). We herein report the preparation (see Experimental and Scheme) of the title compound S-2-adamant-1-yl-4-methylphenyl N,N-dimethylthiocarbamate (I).…”

Tris(2,4-dimethylbenzenethiolato)phenyltin(IV)

“…For background to the development of synthetic methods for highly substituted thiophenols with varying degrees of steric hindrance, see: Lloyd-Jones et al (2008); Fleischer (2005); Huber et al (1997); Estudiante-Negrete et al (2007). For the synthesis of phenol derivatives, see: Flores-Figueroa et al (2005); Mondragó n et al (2010). For similar structures, see: Huber et al (1997); Li et al (2006).…”

“…The development of synthetic methods for highly substituted thiophenols with varying degrees of steric hindrance has been an active field of research (Lloyd-Jones et al, 2008), due in part to the potential of sterically encumbered thiophenols to emulate the active site of sulfur-rich metalloenzymes (Fleischer, 2005). In this context, we developed a series of 2,4-disubstituted thiophenols (Flores-Figueroa et al, 2005, Mondragón et al,2010, among which 2,4-dimethylthiophenol represents a commercially available ligand. In order to assess the steric properties of this thiophenol, we soughtout to prepare a metal-thiolate derivative amenable to structural characterization.…”