Near-term infants had significantly more medical problems and increased hospital costs compared with contemporaneous full-term infants. Near-term infants may represent an unrecognized at-risk neonatal population.
Active titanium metal, produced in a finely divided form by Feduction of Tic13 with either potassium or lithium, will reductively couple ketones and aldehydes to olefins. Although the intermolecular coupling works best when two identical carbonyls are coupled to a symmetrical product, unsymmetrical couplings can also be carried out in certain cases. The unsymmetrical coupling of a diaryl ketone with another partner is particularly efficient, and a mechanism to account for this is proposed. Intramolecular dicarbonyl coupling to form rings is also possible, and the combinaiion TiCls/Zn-Cu works best. Rings of size 4-16 and 22 are prepared in high yield. The nature of the active titanium metal is studied by scanning electron microscopy, and a mechanistic proposal accounting for all observed resulb is presented. It is believed that the coupling reaction occurs on the surface of the active titanium particle.
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