Macrolactonization of hydroxy acids using a polymer bound carbodiimide

Update 1 of: Macrolactonizations in the Total Synthesis of Natural Products

“…(The supported DCU is easily eliminated by a simple filtration. 627 ) The highly basic DMAP is sometimes detrimental to the macrolactonization. For example, in the total synthesis of bryostatin 7, 69 the use of DMAP led to an intractable mixture whereas the use of pyridine in the presence of PPTS 438,628,629 led to the macrolactone in good yield.…”

Efficient Methyl Esterification Using Methoxyl Silica Gel as a Novel Dehydrating Reagent

“…The excess carbodiimides is then converted to dialkyl urea upon completion of the reaction, and thus one must isolate the desired esters from a large amount of the toxic dialkyl urea byproduct. To address these problems, various polymer-supported cou-pling reagents, for example, polymer bound carbodiimide (Scheme I, 1), 3 Mukaiyama reagent (Scheme I, 2), 4 PDMC (Scheme I, 3), 5 triazenes (Scheme 1, 4), 6 triphenylphosphine ditriflate (Scheme I, 5), 7 and O-alkylisourea (Scheme I, 6), 8 have been introduced in the literatures for the preparation of esters. Despite the utility of these reagents, development of simpler, more convenient, and inexpensive reagents is still desired.…”

Preparation of hydroxyapatite/poly(vinyl alcohol) composite film with uniformly dispersed hydroxyapatite particles using citric acid

“…Since the development of efficient pathways applied to modify polymers with functional groups is an essential issue in polymer chemistry,4 the soft and mild association of DCC and DMAP has already been used successfully to prepare not only some polymerizable monomers but also macromonomers and even more complicated functional structures 5…”