Synthesis of oxygen heterocycles by regioselective Heck reaction.

The regioselective Heck arylation of unsaturated alcohols is utilized as the key step in a convenient one-pot procedure for the production of 2,2-disubstituted tetrahydrofurans and tetrahydropyrans. The arylation reaction is effected with a palladium-diphosphine catalyst alongside a hydrogen bond donor; this is followed by the introduction of a Brønsted acid to the reaction mixture, affording the oxygen heterocycles in moderate yields.

Regioselective Heck vinylation of electron-rich olefins with vinyl halides: is the neutral pathway in operation?

Highly regioselective vinylation of electron-rich olefins by bromo- as well as chlorostyrenes is effected by palladium catalysis with either mono- or bidentate phosphines in a molecular solvent, with no need for halide scavengers, ionic liquids, or ionic additives. The use of the hemilabile 1,3-bis(diphenylphosphino)propane monoxide (dpppO) as a ligand led to faster reactions of more challenging 2-substituted vinyl ethers and reduced Pd loadings. In contrast to the related arylation reaction, evidence suggests that the vinylation may proceed via the neutral Heck mechanism.

A response to criticism of our estimates of under-5 mortality in Iraq, 1980-98.

According to estimates published in this journal, the number of deaths of children under 5 in Iraq in the period 1991-98 resulting from the Gulf War of 1991 and the subsequent imposition of sanctions by the United Nations was between 400,000 and 500,000. These estimates have since been held to be implausibly high by a working group set up by an Independent Inquiry Committee appointed by the United Nations Secretary-General. We believe the working group's own estimates are seriously flawed and cannot be regarded as a credible challenge to our own. To obtain their estimates, they reject as unreliable the evidence of the 1999 Iraq Child and Maternal Mortality Survey--despite clear evidence of its internal coherence and supporting evidence from another, independent survey. They prefer to rely on the 1987 and 1997 censuses and on data obtained in a format that had elsewhere been rejected as unreliable 30 years earlier.

Fertility in Kenya and Uganda: a comparative study of trends and determinants.

Between 1980 and 2000 total fertility in Kenya fell by about 40 per cent, from some eight births per woman to around five. During the same period, fertility in Uganda declined by less than 10 per cent. An analysis of the proximate determinants shows that the difference was due primarily to greater contraceptive use in Kenya, though in Uganda there was also a reduction in pathological sterility. The Demographic and Health Surveys show that women in Kenya wanted fewer children than those in Uganda, but that in Uganda there was also a greater unmet need for contraception. We suggest that these differences may be attributed, in part at least, first, to the divergent paths of economic development followed by the two countries after Independence; and, second, to the Kenya Government's active promotion of family planning through the health services, which the Uganda Government did not promote until 1995.

The Strecker reaction: kinetic and equilibrium studies of cyanide addition to iminium ions.

Kinetics studies are reported of the reactions of benzylidene benzylamine 4a, and of benzylidene allylamine 4b, with cyanide in aqueous buffers to give the corresponding [small alpha]-aminonitriles. The results allow the calculation of values of rate and equilibrium constants for reaction of the iminium ions formed from 4a and 4b with cyanide ions. These values are compared with those, obtained from the hydrolysis reactions, for reaction of the iminium ions with hydroxide ions and with water. Comparison with some other iminium ions reveals that those formed from 4a and 4b are relatively unreactive due to the possibilities of charge delocalisation.

The impact of AIDS on adult mortality: evidence from national and regional statistics.

OBJECTIVE: To measure trends in adult mortality in countries with significant levels of HIV prevalence using data sources other than those that collect information on HIV status. DATA AND METHODS: Data sources consisted of national population censuses and sample surveys, Demographic and Health Surveys (DHS), vital registration, and longitudinal surveillance systems. Estimates of adult mortality were derived from censuses using intercensal survival and questions on deaths of household members and orphanhood. From DHS adult mortality was measured from data on survival of siblings and orphanhood. Death registration should be tested for changes in the level of coverage before drawing conclusions on mortality trends. Demographic surveillance systems record trends and age patterns of mortality, but are not nationally representative. RESULTS: Census and survey data from Kenya, Malawi and Zimbabwe showed increasing adult mortality in the 1990s, reversing previous downward trends. DHS data for over 20 sub-Saharan countries showed that most had increasing mortality, which was steepest in eastern and southern Africa, with high HIV prevalences. Death registration in Zimbabwe and South Africa showed increasing adult mortality, as in Thailand and Trinidad, both countries with appreciable levels of HIV. Surveillance systems in Tanzania and South Africa showed radically different age patterns of mortality, with relatively high rates among younger adults compared with data from countries with lower HIV prevalences. CONCLUSION: Adult mortality is increasing in countries with high HIV/AIDS prevalences, although the contribution of the epidemic to this increase is difficult to measure. More data and improved methods of analysis are needed before firm conclusions can be drawn.

Annual mortality rates and excess deaths of children under five in Iraq, 1991-98.

Data from two parallel household surveys conducted in Iraq by UNICEF in 1999 show that under-5 mortality declined steadily from 1974 to 1990, reaching about 63 per 1,000 live births in the period 1986-90. It then rose dramatically to 118 per 1,000 in 1991, the year of the Gulf War. The number of 'excess' under-5 deaths (i.e., the number in excess of the number predicted from past trends) in Iraq between 1991 and 1998 was calculated assuming that, instead of the rates measured by the 1999 survey for this period, either (a) average mortality rates for the period 1986-90 had been maintained, or (b) mortality had continued to decline at the rate observed between 1974 and 1990. According to these calculations, the estimated number of excess deaths resulting from the Gulf War and its aftermath up to 1998 was between 400,000 (assumption a) and 500,000 (assumption b).