Efficient Method for the Esterification of Carboxylic Acids with Alcohols Using Di-2-thienyl Carbonate Promoted by Catalytic Amounts of DMAP and Hf(OTf)<sub>4</sub>
Esterification of carboxylic acids with alcohols including bulky secondary ones by using an equimolar amount of di-2-thienyl carbonate (2-DTC) in the presence of a catalytic amount of 4-(dimethylamino)pyridine (DMAP) followed by addition of a catalytic amount of hafnium(IV) trifluoromethanesulfonate (Hf(OTf)4) afforded the corresponding esters in good to high yields.
Reaction of carboxylicacids with alcohols by using an equimolar amount of di-2-thienyl carbonate (2-DTC) in the presence of a catalytic amount of 4-(dimethylamino)pyridine (DMAP) followed by addition of an equimolar amount of iodine proceeded smoothly to afford the corresponding esters and 2(5H)-thiophenone in good to high yields.
Esterification of carboxylic acids with alcohols by using di-2-thienyl carbonate in the presence of a catalytic amount of 4-(dimethylamino)pyridine (DMAP) proceeded smoothly under mild conditions t...
Disclosed are (1) a cyclic hexapeptide represented by formula [I] or a salt thereof:
wherein X and Y each represent a-amino acid residues, A represents a D-acidic-a-amino acid residue, B represents a neutral-a-amino acid residue, C represents an L-a-amino acid residue and D represents a D-a-amino acid residue having an aromatic ring group; and (2) a pharmaceutical composition comprising the peptide represented by formula [I] or a pharmaceutically acceptable salt thereof as an active ingredient.
Methods and compositions for the prophylactic and/or therapeutic treatment of organ hypofunction
申请人:TAKEDA CHEMICAL INDUSTRIES, LTD.
公开号:EP0626174A2
公开(公告)日:1994-11-30
Compounds having antagonistic activity on endothelin receptors can be effectively used for prophylaxis and/or treatment of hypofunction of organs which occurs in their surgery or transplant.