27015-29-8Relevant articles and documents
A lewis acid-promoted pinner reaction
Pfaff, Dominik,Nemecek, Gregor,Podlech, Joachim
supporting information, p. 1572 - 1577 (2013/10/22)
Carbonitriles and alcohols react in a Lewis acid-promoted Pinner reaction to carboxylic esters. Best results are obtained with two equivalents of trimethylsilyl triflate as Lewis acid. Good yields are achieved with primary alcohols and aliphatic or benzylic carbonitriles, but the straightforward synthesis of acrylates and benzoates starting with acrylonitrile and benzonitrile, respectively, is similarly possible. Phenols are not acylated under these reaction conditions. The method has been used for the first total synthesis of the natural product monaspilosin. In the reaction of benzyl alcohols variable amounts of amides are formed in a Ritter-type side reaction.
Formation of macrocyclic ethers by free radical cyclization: Effects of chain length, substituents, and solvents
Philippen, Annie,Degueil-Castaing, Marie,Beckwith, Athelstan L. J.,Maillard, Bernard
, p. 6814 - 6819 (2007/10/03)
Free radical reduction by tributylstannane of w-iodopolyoxaalkyl acrylates derived from tri-, tetra-, penta-, hexa-, and heptaethylene glycols gives mixtures of uncyclized reduction products and macrocyclic ethers formed by endo cyclization. The rate constants for cyclization of the intermediate radicals at 80 °C in benzene were determined under carefully defined conditions to be 15 × 104,13 ×104,5.1 × 104,10 × 104 and 3.6 × 104 s-1, for formation of the 12-, 15-, 18-, 21- and 24-membered rings, respectively. These values indicate that the presence of oxygen atoms in the chains increases the rate by a factor of 10-30 by comparison with the previously reported cyclization of alkenyl species. The rate constants at 80 °C in benzene and the endo/exo ratio for reductive cyclizations of the methacrylate, crotonate, cinnamate, maleate, and fumarate esters of 8-iodo-3,6-dioxaoctanol have been determined. The reduction of the 8-iodo-3,6-dioxaoctyl acrylate in solvents of varying polarity indicated that the cyclization rate has a relatively low solvent dependence.