Cydopropyl ketones

In contrast, the use of SmI2/DMPU as an electron-transfer system led to the smooth production of spiroketone 3-171a in 79% yield, without any side products (Scheme 3.45). It was also possible to cydize the unprotected cydopropyl ketone 3-170b to give the spiroketone 3-171b in 57% yield. 

A ketolacfcone was isolated. 1 on the other hand, from the condensation of ethylene oxide with carbethoxy methyl cydopropyl ketone in the presence of sodium ethoxide (Eq. S73a). 

Similarly, the thiophene-substituted cydopropyl ketone 1-65 led to the fused ben-zothiophenes 1-67 and 1-68 as a 2 1 mixture. In this process the intramolecular interception of the cationic intermediate 1-66 took place at C-3 and C-5 of the ben-zothiophene moiety (Scheme 1.18). 

Methyl cydopropyl ketone, 576, 823-824 Methyl cydopropyl ketoxime, 1224 fra s-l-Methyldecahydroquinoline, 647... 

Although not formally a type I cleavage process, j3-cleavage of cyclopropyl ketones to form propenyl ketones and/or epimerized cyclopropyl groups bears such a close similarity to a-cleavage that it should be discussed in combination with the latter. The first report of a reaction thought to occur by j3-cleavage was made by Pitts in 1954 for the formation of methyl propenyl ketone from methyl cydopropyl ketone, ... 

Various mechanisms for the 1,2-acyl shift have been proposed, the following three pathways being the most widely discussed a) a Norrish t T)e I cleavage to an acyl and an allyl radical followed by recombination of the radical pair to a cydopropyl ketone or closure of the allyl radical to a cyclopropyl radical, which then recombines with the acyl radical [Eq. 

Allylsilanes have enjoyed widespread use as reagents in allyl-transposition reactions with electrophiles [i.e. ( )- (12)]. Now Sakurai et aV have found that the corresponding homoallylsilanes (13) can be used in the synthesis of cydopropyl ketones (14) from acid chlorides in the presence of Lewis acids. 

In the presence of TiCh, trimethylsilylmethylated cydopropyl ketone 150 undergoes desilylative ring-opening reaction to generate (Z)-enolate 151, which then reacts with dnnamaldehyde, giving rise to syn-adduct 152 stereoselectively (Scheme 5.38) [55]. 

The ambivalent aptitude of sulfur [19] to stabilize adjacent anionic as well as cationic centers is a remarkable fact that has shown to be a reliable feature for the assembly of four-membered ring scaffolds utilizing cydopropyl phenyl sulfides [20], Witulski and coworkers treated the sulfide 1-69 with TsOH in wet benzene (Scheme 1.19) [21]. However, in addition to the expected cydobutanone derivative 1-70, the bicydo[3.2.0]heptane 1-70 was also obtained as a single diastereoisomer, but in moderate yield. Much better yields of 1-71 were obtained using ketone 1-72... 

Highly enantioselective hydrogenation of simple dialkyl ketones is limited to a specific case. Cydopropyl methyl ketone or methyl 1-methylcyclopropyl ketone, for example, can be hydrogenated in 95-98% optical yield in the presence of trans-S)-xylbinap (S)-daipen ",4>RuCl2 (S)-xylbinap (S)-daipen /KOC(CH3)3 [67a, 81c[. 

Cyclopropyl methyl ether Cydopropyl methyl ketone... 

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