Use of the vicinal element effect for regiochemical control of quinone substitutions and its implication for convergent mitomycin construction.

[reaction--see text] Nucleophilic substitution reactions of 2-methoxy-3-alkyl-p-benzoquinones are described as they relate to the construction of the mitomycin backbone. Normally controlled by activating groups attached to the olefin, the observed regioselection in these cases is determined by the deactivating substituent. Approximation of carbonyl activating ability would not have predicted the behavior of two systems investigated in which the poorer of two leaving groups is substituted in each case.

Enantioselective and diastereoselective Mukaiyama-Michael reactions catalyzed by bis(oxazoline) copper(II) complexes.

The scope of highly enantioselective and diastereoselective Michael additions of enolsilanes to unsaturated imide derivatives has been developed with use of [Cu((S,S)-t-Bu-box)](SbF6)2 (1a) as a Lewis acid catalyst. The products of these additions are useful synthons that contain termini capable of differentiation under mild conditions. Michael acceptor pi-facial selectivity is consistent with two-point binding of the imide substrate and can be viewed as an extension of substrate enantioselection in the corresponding Diels-Alder reactions. A model analogous to the one employed to describe the hetero Diels-Alder reaction is proposed to account for the observed relation between enolsilane geometry and product absolute diastereocontrol. Insights into modes of catalyst inactivation are given, including spectroscopic evidence for inhibition of the catalyst by a dihydropyran intermediate that evolves during the course of the reaction. A procedure is disclosed in which an alcohol additive is used to hydrolyze the inhibiting dihydropyran and afford the desilylated Michael adduct in significantly shortened reaction time.

Nonconventional carbon additions to azomethines. aryl amination/indoline synthesis by direct aryl radical addition to azomethine nitrogen.

[reaction: see text]. The generality of a new method for aryl amination has been defined. Ketimines derived from o-bromophenethylamine cyclize to the N-substituted indoline when treated with nBu3SnH and a radical initiator. The pH-neutral conditions tolerate base- and acid-sensitive functionality. The observed regioselectivity is nonconventional for addition reactions involving carbon radicals and carbon-heteroatom pi-bonds.

Comparison of testing saliva and serum for detection of antibody to human immunodeficiency virus in Jamaica, West Indies.

BACKGROUND: In Jamaica the reported incidence of AIDS increased from 0.1/100000 in 1985 to 20.2/100000 in 1995. Here there is great reluctance to have voluntary blood testing and, indeed, any blood testing. Since only enzyme-linked immunoassay (EIA) was available for screening serum HIV-1 and 2 antibody, it was considered that a non-invasive saliva screening EIA could be an advantageous alternative. OBJECTIVE: this study was designed to evaluate the OraScreen HIV Rapid Test, a new, simple saliva screening EIA for anti-HIV-1&2 and to compare its sensitivity and specificity with a standard serum anti-HIV screening EIA in current use in Jamaica. STUDY DESIGN: specificity and sensitivity of HIV antibody assays were compared in matched serum and saliva samples obtained from 257 volunteers from a family planning clinic and from visa applicants, representing a low risk population (Group I), and from 52 volunteers known to be HIV infected (Group II). RESULTS: in Group I, 257 volunteers of unknown HIV status, one was positive for anti-HIV-1 in both serum and saliva. One other was seropositive but negative on saliva testing; confirmatory Western Blot (WB) testing on this serum was negative and this subject was tabulated as blood HIV negative. Fifty-one of the known seropositive volunteers (Group II) were saliva antibody positive. One saliva sample was inadequate and this individual was excluded from the study. Serum samples from three others in Group II were grossly haemolysed but their saliva samples were antibody positive. CONCLUSION: With the exclusion of one subject whose saliva sample was inadequate, the OraScreen HIV Rapid Test showed 100% specificity identifying 256/256 HIV antibody negative individuals, and 100% sensitivity by identifying 52/52 infected individuals as HIV antibody positive.

Catalytic enantioselective Michael additions to unsaturated ester derivatives using chiral copper(II) Lewis acid complexes.

[formula: see text] Chiral Cu(II) bisoxazoline (box) Lewis acids have been developed as catalysts of the Michael addition of enolsilanes to unsaturated ester derivatives. While enantioselection is stereoregular, the sense of diastereoselection is directly related to thioester enolsilane geometry: (E) enolsilanes give anti adducts and (Z) enolsilanes afford syn adducts. The size of the enolsilane alkylthio substituent directly impacts the magnitude of diastereoselection.

Effects of a selective beta 2-blocker (ICI 118,551) on hepatic haemodynamics in the cirrhotic and non-cirrhotic rat.

The effects of a selective beta 2-blocker (ICI 118,551) on hepatic haemodynamics were studied in cirrhotic and non-cirrhotic rats. Infusions of 10 and 20 microgram (kg body wt)-1 min-1 beta 2-blocker (in cirrhotic and non-cirrhotic rats) significantly reduced portal pressure, portal venous flow and liver blood flow without altering heart rate. Splanchnic vascular resistance was significantly increased following infusions of 10 and 20 micrograms (kg body wt)-1 min-1 beta 2-blocker. An intraportal injection of beta 2-blocker (10 micrograms body wt)-1 or hepatic artery ligation lowered portal pressure by approximately the same magnitude. Intraportal injection of beta 2-blocker after hepatic artery ligation did not further reduce portal pressure. The results indicate that a selective beta 2-blocker reduces portal pressure by a combination of increased splanchnic vascular resistance and hepatic arterial resistance. It is concluded that a selective beta 2-blocker may be of clinical value in the long-term managements of portal hypertension.