Enones synthesis

Enantiomers, preferential crystallization of 59 Endo selectivity 798 Ene reactions 808, 809 Enones, synthesis of 732 Enthalpies of formation 102, 103 Enynes, synthesis of 956 Enzymatic kinetic resolution 829 Epimerization 399 Episulphides, oxidation of 237 Episulphones 650, 775 Episulphoxides, photolysis of 742 a,/J-Epoxysulphones reactions of 811, 812 rearrangement of 685 synthesis of 612 / ,y-Epoxysulphones 781 y,<5-Epoxysulphones 627, 628 Epoxysulphoxides reactions of 613 rearrangement of 744 synthesis of 327, 612 Erythronolides 831... 

Palladium-catalyzed conversion of enol silanes to enones, also known as the Saegusa enone synthesis. 

We have expanded our collection of stereoselective reactions even more in the making of alkenes by the Wittig reaction (chapter 15), from acetylenes (chapter 16), by thermodynamic control in enone synthesis (chapters 18 and 19) and in sigmatropic rearrangements (chapter 35). We have seen that such E- or Z-alkenes can be transformed into three-dimensional stereochemistry by the Diels-Alder reaction (chapter 17), by electrophilic addition (chapters 23 and 30), by carbene insertion (chapter 30) and by cycloadditions to make four-membered rings (chapters 32 and 33). 

Figure 8 Bicyclic enone synthesis by conjugate addition and aldol reaction.

In the more general enone synthesis 89 - 102 - 105, the original anion of the bis-(phenyl-thio) acetal 89 behaves as a vinyl dianion (R CH=C2- ), an interesting complement to syn-thons 37 and 58... 

Schreiner, E. P. Pruckner, A., Syrc-Selective Michael Addition of Amines to Bis-Enones Synthesis of 1,3,4,7-Tetrasubstituted (4R, 5S, 6S, 7R)-Hexahydro-5,6-dihydroxy-2H-l,3-diazepin-2-ones J. Org. Chem. 1997, 62,5380. 

Kuroda, C., Nogami, H., Ohnishi, Y., Kimura, Y.. and Satoh. J.Y. Stereochemistry of Lewis acid and fluoride promoted intramolecular cychzation of P-(alkoxycarbonyl)allylsilane with enones. Synthesis of bicyclo[4.3.0]nonanes. Tetrahedron. 53, 839, 1997. 

An example with two enones made by different strategies Strategic bonds in enone synthesis Rearrangements ofallylic alcohols with Cr(VI)... 

Unsubstituted vinyl-lithium and vinyl Grignard 14 reagents can be made directly from the halide by oxidative insertion of Li(0) and Mg(0). Vinyl-lithium is available as a 2M solution in THF from Alfa and vinyl magnesium bromide, which must be prepared in THF, is available in THF from Aldrich. These are quite stable o-complexes because alkenyl anions are more stable than saturated alkyl anions. They add as nucleophiles to carbonyl groups, e.g. cyclobutanone to give 15 and prefer direct to conjugate addition with enones to give e.g. 13. We have already used them in enone synthesis (chapter 5). 

---