Stille reaction analogues

Stille employed a Heck reaction on triflate 136 to install the acrylamide side chain in his synthesis of anthramycin and analogues, as illustrated below [79, 80]. Ironically, a Stille reaction was less efficient in this transformation. 

Sn2 substitution using organocopper reagents is an efficient method for the synthesis of 3-substituted olefins. In the synthesis of famesyl diphosphate analogues (43j 45) as potential inhibitors of the enzyme protein-famesyl transferase for example organocopper methodology was compared with the StilLe reaction [33] and the Suzuki reaction [34] frequently used in the coupling of vinyl triflates with... 

The fragmentation in the MALDI-TOF MS experiment noted from the brominated polymer is less prevalent in this chlorinated material, but evidence for the lactone-ended oligomer (7) is still noted (see Figure 8). Evidence for the competing disproportionation mechanism is again provided by the presence of peaks proposed to be from unsaturated (8) and saturated (9) end-functionalised oligomer [10]. The data indicate that this disproportionation reaction is a minor termination pathway, as low intensity peaks are noted for 8 and 9 (as for 4 5 from the brominated analogue). 

The number of turnovers (10) in hydrocarbon production without apparent decrease in activity proved that the reaction was indeed catalytic. The IR spectrum of the recovered resin showed small absorptions due to CpCo(C0)2 5 due to some recar bony la-tion of " CpCo". In addition, a broad distinct band at 1887 cm"l was seen. The identity of the species exhibiting this carbonyl band is still a mystery in particular, the band position does not match that reported for any of the CpCo (CO) 2 -derived di- and trinuclear carbonyls (vide supra). It is tempting to associate this band with seme catalytic intermediate, such as the polymer-bound analogues of CpCo(H)2(C0) and CpCo(HKPh)(CO), but this is pure speculation. 

Despite the development of some new methods for this strategy of bicyclic system formation, the intramolecular C-acylation of pyrrole is still frequently employed. This reaction may be performed starting from W/Tcyanoethyl-pyrroles as well as starting from their acid, ester, and even amide analogues. 

Only two stable fluorine oxides are known. Except for an early investigation of the decomposition of F202, studies of decomposition kinetics have been confined to F20. There still remains considerable doubt concerning the mechanisms by which these two compounds decompose to their elements. Unlike its chlorine analogue, FO has defied spectroscopic detection in the fluid phases, although it is considered an important intermediate in many of the reactions of F20. 

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