Categories: C-O Bond Formation >
Synthesis of carbonates and related compounds
Mg(ClO4)2 is a stable and specific activator of 1,3-dicarbonyl compounds, that allows a smooth, direct synthesis of aryl and alkyl ethyl carbonates.
G. Bartoli, M. Bosco, A. Carlone, M. Locatelli, E. Marcantoni, P. Melchiorre, P. Palazzi, L. Sambri, Eur. J. Org. Chem., 2006, 4429-4434.
Treatment of 4,5-dichloro-6-oxopyridazin-1(6H)-carboxylates with aliphatic or aromatic alcohols in the presence of potassium tert-butoxide in toluene at room temperature provides carbonates in good yields. Alkyl and aryl 4,5-dichloro-6-oxopyridazin-1(6H)-carboxylates are therefore efficient, stable, and ecofriendly alternatives to chloroformates.
H. K. Moon, G. H. Sung, Y.-J. Yoon, H. J. Yoon, Synlett, 2016, 27, 1577-1581.
A very efficient Zinc acetate-catalyzed protection of alcohols as Boc derivatives can be applied to primary, secondary and aromatic alcohols, providing the first example of a generally applicable method.
G. Bartoli, M. Bosco, A. Carlone, R. Dalpozzo, M. Locatelli, P. Melchiorre, P. Palazzi, L. Sambri, Synlett, 2006, 2104-2108.
A photo-on-demand in situ synthesis of chloroformates of primary alkyl alcohols in the presence of CHCl3 and oxygen followed by addition of alcohols or amines enables a one-pot synthesis of carbonates and carbamates, respectively.
F. Liang, M. Yanai, Y. Suzuki, A. Tsuda, Org. Lett., 2020, 22, 3566-3569.
Carbon tetrabromide catalyzes O-tert-butoxycarbonylation of functionalized phenols without any side reactions (bromination, addition of CBr3 to a double bond, and formation of symmetrical diaryl carbonates, cyclic carbonates, or carbonic-carbonic anhydrides). The parent phenols are regenerated from the O-t-Boc derivatives by the catalyst system CBr4-PPh3 without affecting other functional groups.
S. V. Chankeshwara, R. Chebolu, A. K. Chakraborti, J. Org. Chem., 2008, 73, 8615-8618.
Triphenylphosphine is a suitable organocatalyst for the chemoselective O-tert-butoxycarbonylation of phenols under neutral and neat conditions.
R. Chebolu, S. V. Chankeshwara, A. K. Chakraborti, Synthesis, 2008, 1448-1454.
The reaction of Grignard reagents with alkyl imidazolecarboxylates, which were prepared from alcohols with carbonyl diimidazole, gave the corresponding esters in good to excellent yields.
T. Werner, A. G. M. Barrett, J. Org. Chem., 2006, 71, 4302-4304.
An efficient method to activate hydroxyl groups of amino alcohols has been developed, which avoids the use of toxic reagents and tolerates various functional groups. This strategy has been applied to the synthesis of functionalized p-methoxyphenyl-protected azetidines, pyrrolidines, and piperidines.
R. M. de Figueiredo, R. Fröhlich, M. Christmann, J. Org. Chem., 2006, 71, 4147-4154.
A bimetallic titanium complex [(salen)TiO]2 catalyzes the asymmetric addition of ethyl cyanoformate to aldehydes leading to cyanohydrin carbonates with high enantiomeric excesses.
Y. N. Belokon, A. J. Blacker, L. A. Clutterbuck, M. North, Org. Lett., 2003, 5, 4505-4507.