Ketones, cyclic from diesters

Acyloin condensation Formation of cyclic a-hydroxy ketones from diesters. 4... 

This reaction has been used to synthesize cyclic ketones of intermediates to a large ring from diesters with long hydrocarbon chain between two ester groups. ... 

A two-carbon ring expansion of cyclic ketones was achieved by the addition of acetylenic esters and diesters to the enamine derivatives of the ketones, and reported almost simultaneously from several laboratories (337-343). The intermediate bicyclic adduct could be isolated in some cases. 

Scheme 4.18 a,co-Diesters from cyclic aliphatic ketones. 

A number of linear and cyclic alkenes have been studied in this reaction. The presence of a base favoured the formation of diesters from linear alkenes, whereas cyclic alkenes gave diesters even in absence of base.519 In a further study using dienes and unsaturated alcohols, ketones and esters, the dicarboxylation reaction could quite generally be achieved in good yields.S20S21... 

A variation on this reaction is when the anion is formed from the diester derivative of 4-butandioic acid (succinic acid). In this case, the reaction proceeds via an intermediate that is a cyclic ester (i.e. a lactone). Write down the mechanism for the reaction between a general ketone, R CK), and the... 

Rare examples of normal Michaelis-Becker reactions which involve co-chloroalkanal diethyl acetals are to be found, and although the formation of dialkyl acylphosphonates from sodium dialkyl phosphites and, for example, benzoyl chloride, is to be observed at -85 °C, the system is further complicated, even at -10 °C, by further addition steps followed by rearrangements which would seem to render the process of little value for the synthesis of oxoalkyl phosphonic esters On the other hand, in a more detailed and systematic study of reactions between sodium dialkyl phosphites, (RO)2PONa(R = Et or Bu), and the ketones R CO(CH2) Cl, Sturtz and others have observed the formation of epoxides when n = 1 and (1-hydroxy alk-2-enyl)phosphonic diesters when n = 2(R = Me or Pr ), according to the displacement in 532, and of derivatives of tetrahydrofuran or tetrahy-dropyran, according to 533 n = 3 or 4) when R = Et, the formation of the cyclic ethers was accompanied by low yields of the expected (oxoalkyl)phosphonic diester, but otherwise the latter were isolated as a single product only for R = Me, n = 5, and R = Et or Pr when n = 2. 

This reaction was first reported by Bouveault and Blanc in 1903, and was further extended by Bouveault and Locquin. It is the synthesis of symmetrical a-hydroxy ketones via the reductive condensation of esters in an inert solvent in the presence of sodium. Since symmetrical a-hydroxy ketones, the aliphatic analogs of benzoins, are generally known as acyloins, the formation of a-hydroxy ketones from esters is simply referred to as acyloin condensation. In a few cases, it is also referred to as acyloin reaction." For the individual acyloin, the name is derived by adding the suffix oin to the stem name of corresponding acid, e.g., acetoin prepared from acetate. The most common method used to make acyloin is the reductive condensation of aliphatic esters with sodium in inert solvents, such as ether, xylene or even in liquid NH3 The yield of this reaction can be greatly improved when trimethylchlorosilane presents." " Intromolecular acyloin condensation from aliphatic diesters affords cyclic ketones of different ring sizes. 

Finally, oxidative carbonylations of simple ketones, such as hexanone and pentanone, were reported to give diesters [42,43]. In the presence of PdCl2, CUCI2, CO, and in methanol, various diesters have been produced in good yields from corresponding cyclic ketones. 

The addition of diester 178 to cyclic enone was apphed by Plaquevent et al. in the synthesis of methyl dihydrojasmonate, a natural ketone with olfactory properties isolated from Jasminum grandiforum L (Scheme 11.43). Despite the relatively moderate 80% ee and large excess of dimethyl malonate required (30 equiv), the rapidity of the synthesis (two steps to the natural product) and the simple reaction conditions remained attractive for scaleup. 

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