thiourea and benzotriazole

Monitoring of mechanochemical thiocarbamoylation by in situ Raman spectroscopy revealed the formation of aryl N-thiocarbamoylbenzotriazoles, reactive intermediates deemed unisolable in solution. The first-time isolation and structural characterization of these elusive molecules demonstrates the ability of mechanochemistry to access otherwise unobtainable intermediates and offers a new range of masked isothiocyanate reagents.

Topics: Crystallography, X-Ray; Indicators and Reagents; Isothiocyanates; Models, Molecular; Spectrum Analysis, Raman; Thiourea; Triazoles

Organic reactions performed in the absence of solvent in domestic ovens without appropriate temperature control are generally considered as not reproducible, particularly when different instruments are used. For this reason, reproducibility has historically been one of the major issues associated with Microwave-Assisted Organic Synthesis (MAOS) especially when domestic ovens are involved. The lack of reproducibility limits the general applicability and the scale up of these reactions. In this work several solvent-free reactions previously carried out in domestic ovens have been translated into a single-mode microwave reactor and then scaled up in a multimode oven. The results show that most of these reactions, although not considered as reproducible, can be easily updated and applied in microwave reactors using temperature-controlled conditions. Furthermore, computational calculations can assist to explain and/or predict whether a reaction will be reproducible or not.

Topics: Alkylation; Aniline Compounds; Bromides; Chemistry, Organic; Combinatorial Chemistry Techniques; Microwaves; Oxidation-Reduction; Pyridines; Reproducibility of Results; Temperature; Thiourea; Triazoles; Urea

1-(Alkyl/arylthiocarbamoyl)benzotriazoles 4a-i were synthesized in yields of 91-99% from bis(benzotriazolyl)methanethione (3). Reagents 4a-g were then used as isothiocyanate equivalents for the efficient synthesis of 10 secondary and 14 tertiary thioureas in high-yielding, convenient processes.

Topics: Isothiocyanates; Molecular Structure; Tetrazoles; Thiocarbamates; Thiourea; Triazoles