Intramolecular alcoholysis

What is the effective molarity of imidazole as an intramolecular general base in intramolecular alcoholysis and hydrolysis This is perhaps the most important single piece of information that is currently missing for analysis of the rates of a-chymotrypsin reactions in terms of specific catalytic effects. 

Amino-6-chloromethyl- (248) gave 3-amino-6-butoxymethyl-2-pyrazinecar-bonitrile (249) (BuOH, reflux, 12 days 77% or likewise, 2 days 58%).612 Also other examples 53,391,871,957 1059,1139 for examples of intramolecular alcoholysis (epoxide formation) see end of this section. 

The Pd(II) complex (41) promotes stoichiometric alcoholysis of urea according to Scheme 8, giving the carbamate esters of the ligand (101). For methylurea as the substrate, the major product is the one with R = H (75%), while the product with R = Me is the minor one (25%). This intramolecular alcoholysis is 240-380 times faster than the intermolecular alcoholysis involving external attack of free ethanol. The O-bound 1,3-dimethylurea does not undergo any detectable intramolecular or catalytic alcoholysis, since the N-bound isomer, which is the much more reactive one, is practically absent due to steric reasons. 

Lipase-catalyzed enantiomer-differentiating inter- and intramolecular alcoholysis of acylated alcohols and lactones in organic solvents may most advantageously be used instead of hydrolysis in aqueous solution in those cases where insufficient stability, high solubility or low functional group selectivity is observed or may be anticipated in the latter case (1-16) (TSble 11.1-22). 

Table n.1-22. Lipase-catalyzed enantiomer- and enantiotopos-differentiating inter- and intramolecular alcoholysis of esters and lactones in organic solvents (PCL Pseudomonas cepacia lipase, PSL Pseudomonas sp. lipase, PPL pig pancreas lipase, MML Mucor miehei lipase, HLL, Humicola lanuginosa lipase, PFL Pseudomonasfluorescens lipase, CCL Candida cyiindracea lipase, CAL-B Candida antarctica B lipase, CRL Candida rugosa lipase, PRL Penicillium roquefbrti lipase, CAL-A+B Candida antarctica A+B lipase). 

The alkoxylation process is easy to apply to PU foams having a low concentration of urethane and urea groups such as flexible and semiflexible foams, integral skin foams, PU elastomers and so on. Urea groups react in a similar way with urethane groups, with the formation of oxazolidones and amines by an intramolecular alcoholysis of urea groups (reaction 20.15). 

A number of aryl 3 -uridylyl phosphorothioates have been prepared, using a new method involving the 3 -H-phosphonate as an intermediate the kinetics of base catalysis and leaving group dependence in the intramolecular alcoholysis of the phosphorothioates was studied. The 3 -phenylphosphonates of adenosine and uridine have been made and evaluated as substrates of 3 -nucleotidases. Reaction of thymidine with an oxyphosphorane was used to make thymidin-3 -yl benzoin phosphate. ... 

---