O-propargyl derivatives

Some examples of the lateral cyclization of suitable O-allyl and O-propargyl derivatives were discussed in CHEC-11(1996) <1996CHEC-II(8)747>. Thermal reaction of silyl diazoacetate 303 in xylene provides unspecific decomposition and a minor amount (about 2%) of a colorless solid can be precipitated with ether. The X-ray diffraction analysis identified the structure 305, which is a product of the lateral criss-cross cycloaddition of primarily formed azine 304 (Scheme 43) <2000T4139>. 

Although polynuclear alkyne completes are often prepared by reaction of the alkyne with a suitable metal cluster fragment, heteropolynuclear complexes 69 (Scheme 4-38) have been obtained also by isolobal metal fragment substitution, as noted previously [26]. Higher-nuclearity alkyne complexes also can be produced by the addition of various metal carbonyl fragments to a lower-nuclearity alkyne complex [119], A novel entry to heterobi- (and tri-)metallic neutral p-propargyl complexes (e.g., Fe/Mo) via protonation of trinuclear p-Ti, T1 -o-propargyl derivatives 70 was recently described by Wojcicki and coworkers [120,121]. 

To confirm whether multidentate calixarenes could limit NP growth under solvothermal conditions, we prepared hexadecanuclear cobalt complexes 1 and 2 from Co2(CO)g, a common precursor for Co NP synthesis, and octa-O-propargyl derivatives of Cl and Cll resorcinarene (3 and 4 respectively) [14, 15]. Coje-calixarenes 1 and 2 were stable under ambient conditions, but decomposed rapidly above 90 °C. An x-ray crystal stmcture of 1 shows all eight pendant Co2(CO)e units to be on the same face of the calixarene platform [14], and MALDl-MS analysis of 2 indicates facile decarbonylation into zerovalent Coie clusters [15], implying formation of a metastable capped-cluster intermediate (Fig. 34.3). 

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