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Mild and High‐Yielding Molybdenum(VI) Dichloride Dioxide‐Catalyzed Formation of Mono‐, Di‐, Tri‐, and Tetracarbamates from Alcohols and Aromatic or Aliphatic Isocyanates
Author(s) -
Stock Christian,
Brückner Reinhard
Publication year - 2012
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201200303
Subject(s) - chemistry , catalysis , molybdenum , dimethylformamide , solvent , organic chemistry , steric effects , alcohol , polymer chemistry , medicinal chemistry
Both molybdenum(VI) dichloride dioxide (MoO 2 Cl 2 ) and its dimethylformamide (DMF) complex catalyze the addition of alcohols to isocyanates giving carbamates. Most additions proceeded to completion at room temperature within 20 min using as little as 0.1 mol% of the catalyst when working on a 1‐mmol scale or just 100 ppm working on a 20‐mmol scale. Sterically encumbered substrates reacted to completion when 1 mol% of the catalyst was employed. Diols, triols, and tetraols reacted with monoisocyanates likewise, as did monofunctional alcohols and diisocyanates. These pairings furnished di‐, tri‐, tetra‐, and dicarbamates, respectively. Reactants, which were poorly soluble in CH 2 Cl 2 at room temperature required elevating the temperature and possibly choosing a higher‐boiling solvent (ClCH 2 CH 2 Cl, DMF) as well. Additions of diols to diisocyanates were feasible, too, giving polycarbamates as we presume.