Synthesis from ketones

Vinyl iodides. A convenient synthesis from ketones features enolphosphoryla-tion and treatment of the products with MejSil (or MejSiCl-Nal in MeCN) for a few minutes at room temperature. 

C-nucIeophilicity, 13-14 oxidative cleavage, 285 Robinson anellation of, 73, 298 synthesis from ketones, 13, 88 by oxn. of ten. amines, 138-139 Enantiofaces definition, 359... 

Scheme 2.6 Pd-catalyzed benzofuran synthesis from ketone.

We could have disconnected bond b to a cation such as 21 and acyl anion 22. This disconnection, however, does not rely on the normal polarity of the carbonyl group. This does not mean that the synthesis could not be done this way. Chloroketone 23 and cyanide (24) are real world versions of 21 and 22, respectively. A displacement reaction followed by ethanolysis of the ce-cyanoketone might provide 16. Chloroketone 23, however, is a difunctional compound. Two methods for preparing 23 are shown. The synthesis from ketone 25 makes use of the normal polarity of the carbonyl group. The synthesis from carbon fragments 27 and 28 makes use of an A-function. 

The application to the saturated methyl ketone (83) of Wilds method of constructing ring D (Scheme 10) gave derivatives of 16-oxoestrone [188] (see Scheme 6). The alkylation of ketone (83) with bromoacetic ester and the reaction of the chloride of the acid formed (103) with sodiomalonic ester and decarboxylation led to the diketone (104). An attempt at its direct synthesis from ketone (83) by alkylation of the latter with chloro- or bromo-acetone was unsuccessful. The intramolecular cyclization of ketone (104) by the action of alkali yielded the -ketone (107), hydrogenation of which led to the isolation of one isomer of the 16-ketone (106) of unknown configuration [188]. The construction of a side chain at C14 of the methyl... 

SCHEME 1.20 Tentative assistance of hydroxylamine to the one-pot pyrrole synthesis from ketones, hydroxylamine, and acetylene. 

The generality of pyrrole synthesis from ketones (ketoximes) and acetylenes is well illustrated by its successful application for the synthesis of such exotic, hitherto unknown, or hardly available representatives of pyrroles such as adamantylpyrrole [130], ferrocenylpyrrole [131], para-cyclophanylpyrrole [132], l,4-bis-(N-vinylpyr-rol-2-yl)benzene [133], and dipyrrolylpyridine [134] (Scheme 1.3). 

Scheme 4.52 Mechanism for Ij mediated 1,2,3-triazole synthesis from ketones, N-tosylhydrazines, and amines.

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