Additions to Ketones

1) We might suggest that a (-hydride elimination occurs to give the ketone, something that we have observed with Pd catalysis under Sole s conditions (Viana, H.R., Gilmore, K., Burke, A.J. (2014) unpublished results). 

Since fluorinated compounds have found extensive application in the materials, agrochemicals, and pharmaceutical fields [32], despite a plethora of methods existing in the literature concerning 

3-Substituted-3-hydroxyoxindoles represent a fertile ground for drug discovery as seen by the recent number of articles published concerning their isolation, bioactivity, synthesis, and medicinal 

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Addition of pyrazole to C—X double bonds is also common. Formaldehyde gives stable adducts (260) and (261) (69BSF2064), but in the addition to ketones, (262) is only observed at low temperatures (Section 4.04.1.3.3(i)). However, hexafluoroacetone forms a stable adduct (262 R = Cp3) that has been used as a chelating agent (Section 4.04.2.1.3(iv)). Addition of pyrazoles to aryl isocyanates affords (263) the addition is also reversible, but it requires high temperatures to dissociate the adduct (Section 4.04.1.5.1). 

I. ORGANOMETALLIC ADDITIONS TO KETONES, CONJUGATED KETONES AND EPOXIDES... 

The most widely used variant of the Gabriel-Colman is the conversion of saccharine derivatives to benzothiazine derivatives. The reaction has been extensively studied as benzothiazines are important pharmacophores, particularly in the oxicam class of antiinflammatories. The first reported instance of this transformation was in 1956 where 43 was treated with sodium methoxide to provide 44. The rearrangement also works with esters " and some amides " in addition to ketones. 

In addition to ketone enolates, azaenolatcs with chiral auxiliary groups attached to the nitrogen atom are suitable for the introduction of an a-unsubstituted enolate of the keto-type into an aldehyde in a stereoselective manner (see Section D.1.3.5.). 

On page 94 appeared a problem on the synthesis of acid (1), needed for conversion to ketone (2), The problem under investigation was sterlc hindrance in nucleophilic additions to ketones and a crowded ketone with a chiral centre was needed. 

Henry reactions 317-20 hydrosilylations 333 organozinc reagents, addition to ketones 156-80 PrMgCl to cyclohexenone with crown thioether ligands 100-1 see also specific ZnEt2 and ZnR2 addition reactions... 

The initial products of such additions under aprotic conditions are organosamarium reagents and further (tandem) transformations are possible, including addition to ketones, anhydrides, or carbon dioxide. 

All three previously mentioned issues associated with the Medicinal Chemistry route were rooted in cyclopropylacetylide (37) addition to the ketone 36. Other steps in the Medicinal route are suitable for large scale preparation. Thus, our effort for this process development focused on asymmetric addition to ketone 36 with close to 1 equiv of 37 [21],... 

Table 1.5 Amino alcohol-mediated addition to ketone 41.

As mentioned in the introduction, there are conflicting views as to the contributions made to polymer degradation by various initiating species. Among these species, in addition to ketones, hydroperoxides are some of the more important chromophores. As it is known, the photolysis of hydroperoxides yields alkoxy and hydroxy radicals. In polymers, in the presence of oxygen, these radicals lead to the secondary formation of peroxy radicals. The latter in turn are converted by hydrogen abstraction into new hydroperoxides (Scheme I) ... 

This preparation is patterned after the in situ preparation of dibromomethyllithium for addition to ketones using lithium dicyclohexylamide, as reported by Taguchi, H. Yamamoto, H. Nozaki, H. J. Am. Cham. Soc. 1974, 96, 3010. 

Highly Reactive Calcium for the Preparation of Organocalcium Reagents Preparation of 1-Adamantyl Calcium Halides and Their Addition to Ketones. 

Organometallic compounds or carbanions undergo a number of reactions in which the carbanion or carbanion-like moiety of the organometallic compound acts as a nucleophilic displacing agent. Examples are the formation of hydrocarbons from alkyl halides, alkyl halides from halogens, and ketones from acid chlorides or esters. The latter two reactions are closely related to the base-catalyzed condensations and are perhaps additions as well as displacement reactions. Related addition reactions are the carbonation of organometallic compounds and the addition to ketones or aldehydes. 

In situ magnesiation of an allenyl iodide with isopropylmagnesium bromide gives rise to a transient allenyl Grignard reagent, which adds to aldehydes and ketones to afford mainly homopropargylic alcohol adducts (Table 9.8) [18]. The anti diastereo-mers are favored, especially with sterically demanding aldehydes. Additions to ketones are less selective. 

Although both boronates and alanates react with allylic bromides, aldehydes and C02 to afford allenic products in satisfactory yield, the alanates are more efficient in additions to ketones (Table 9.14). Boronate reagents do not require a B-C alkyl migration for their preparation. Thus the starting acetylene possesses the structural elements of the product. Additionally, the issue of dummy ligands is irrelevant. 

In situ transmetallation of allenylpalladium intermediates with Sml2 provides a route to allenylsamarium reagents [123]. These undergo protonolysis with alcohols to afford mainly allenes (Table 9.59). Additions to ketones yield either allenylcarbi-nols (A) or homopropargylic alcohols (B) depending on the allene substituents (Table 9.60). 

R. D. Rieke, T.-C. Wu, and L. 1. Rieke 147 HIGHLY REACTIVE CALCIUM FOR THE PREPARATION OF ORGANO-CALCIUM REAGENTS PREPARATION OF 1-ADAMANTYL CALCIUM HALIDES AND THEIR ADDITION TO KETONES 1 -(1 -ADAMANTYLJCYCLOHEXANOL... 

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