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Paul W Davies

Publications and source records attributed to Paul W Davies.

6 recordsLinked to original sources
PubMed2005

Heterocycles by PtCl2-catalyzed intramolecular carboalkoxylation or carboamination of alkynes.

PtCl2 constitutes a convenient catalyst for intramolecular hydroalkoxylation, carboalkoxylation, hydroamination, and carboamination reactions of alkynes, effecting the formation of substituted benzo[b]furan, indole-, and isochromene-1-one derivatives, respectively. This procedure allows for the transfer of (substituted) allyl, methoxymethyl (MOM), benzyloxymethyl (BOM), and (trimethylsilyl)ethoxymethyl (SEM) groups from oxygen to carbon and is compatible with functional groups that are susceptible to oxidative insertion of low valent metal species previously used for similar purposes. Although some of the reactions can even be carried out in air, the rates are significantly increased when conducted under an atmosphere of CO. A mechanistic rationale is proposed, implying activation of the alkyne by the carbophilic Pt(2+) template as the primary step of the catalytic cycle.

Journal Article↗
PubMed2005

Cyclobutenes by platinum-catalyzed cycloisomerization reactions of enynes.

1,6-Enynes bearing (electron-rich) aryl substituents on their alkyne moiety rearrange to cyclobutene derivatives in the presence of catalytic amounts of PtCl2 in toluene. The reaction is significantly accelerated when performed under an atmosphere of CO (1 atm), most likely by increasing the electrophilicity of the metal template by temporary coordination to this pi-acidic ligand. This transformation allows the build up of considerable strain in the products as witnessed by the productive formation of tricyclic skeletons, such as 7 or 9. Moreover, these products provide evidence for the mechanistic scenario of platinum-catalyzed cycloisomerization reactions previously proposed, which are thought to proceed via organo-platinum species that mimic the reactivity of metal-complexed "nonclassical" carbocations.

Journal Article↗
PubMed2005

Alkyne metathesis.

This review discusses the emergence of alkyne metathesis as a valuable synthetic tool applicable in the synthesis of complex molecules and polymer science.

Alkynes↗
PubMed2005

Oral herpes simplex reactivation after intrathecal morphine: a prospective randomized trial in an obstetric population.

There is now evidence for an association between the use of epidural morphine and reactivation of herpes simplex labialis (HSL). There are no studies that definitively demonstrate the relationship between HSL reactivation and spinal intrathecal morphine. To investigate this relationship, we randomized and prospectively studied 100 obstetric patients with a history of HSL undergoing cesarean delivery under spinal anesthesia. One group received intrathecal morphine plus IV morphine via patient-controlled analgesia (ITM+PCA group) for postoperative analgesia, and a second group received only IV morphine via patient-controlled analgesia for postoperative analgesia (PCA-only group). Patients were followed for a 30-day period. In the ITM+PCA group 19 (38%) patients had HSL reactivation whereas eight (16.6%) had HSL reactivation in the morphine PCA-only group (P = 0.028). The incidence of pruritus in the ITM+PCA group was also more frequent in the early postoperative period. Our data show HSL reactivation in both the ITM+PCA group and PCA-only morphine group, with a more frequent incidence in the ITM+PCA group.

Analgesia, Patient-Controlled↗