Cycloalkanones, alkylidene

Compounds i, ii, and iii can be prepared by an acid-catalyzed reaction of a diol and the cycloalkanone in the presence of ethyl orthoformate and mesitylene-sulfonic acid. The relative ease of acid-catalyzed hydrolysis [0.53 M H2SO4, H2O, PrOH (65 35), 20°] for compounds i, iii, acetonide, and ii is C5 C7 > acetonide C (e.g., t.//s for 1,2-O-alkylidene-a-D-glucopyranoses of C5, C7, acetonide, and C derivatives are 8, 10, 20, and 124 h, respectively). The efficiency of cleavage seems to be dependent upon the electronic environment about the ketal. ... 

Of the many substituted and functionalized alkenes that have been combined with diazo dipoles to give A -pyrazolines or products derived from them (i.e., A -pyrazolines, pyrazoles, cyclopropanes), only a selection will be mentioned. These include ot-alkylidene-cycloalkanones (62), -flavanones, -thioflavanones, -chroma-nones, and thiochromanones (63,64) a-arylidene-indanones and -indolones (65) diarylideneacetones (66) l-benzopyran-2(77)-ones (coumarins) (67,68) 4-nitro-1,2-oxazoles (69) 2-alkylidene-2-cyanoacetates (70) dimethyl 2,3-dicyanofuma-rate (71) tetracyanoethylene (72) tetraethyl ethylenetetracarboxylate (72) 1,4-quinones (35,73-75) 2-X-l,l,l-trifluoro-2-propene [X = Br, (76), SPh, SOPh, S02Ph (77)] nitroalkenes (78) including sugar nitroalkenes (79) 1-diethoxyphos-phoryl-1-alkenyl-sulfoxides (80) methyl 2-(acetylamino)cinnamate and -acrylate... 

The attempted epoxidation of a-alkylidene cyclic sulfones led directly to enlarged sulfonyl cycloalkanones [210]. The rearrangement step is thermodynamically controlled in that products contain an a-d-a sequence. 

This topological rule readily explained the reaction product 211 (>90% stereoselectivity) of open-chain nitroolefins 209 with open-chain enamines 210. Seebach and Golinski have further pointed out that several condensation reactions can also be rationalized by using this approach (a) cyclopropane formation from olefin and carbene, (b) Wittig reaction with aldehydes yielding cis olefins, (c) trans-dialkyl oxirane from alkylidene triphenylarsane and aldehydes, (d) ketenes and cyclopentadiene 2+2-addition, le) (E)-silyl-nitronate and aldehydes, (f) syn and anti-Li and B-enolates of ketones, esters, amides and aldehydes, (g) Z-allylboranes and aldehydes, (h) E-alkyl-borane or E-allylchromium derivatives and aldehydes, (i) enamine from cyclohexanone and cinnamic aldehyde, (j) E-enamines and E-nitroolefins and finally, (k) enamines from cycloalkanones and styryl sulfone. 

Silverstein and coworicers have used the peroxy acid oxidation of exo-alkylidene cycloalkanones as a route to keto acids (Scheme 23). Oxidation of pulegone (72) and hydrolysis of the derived enol lactone led to the keto acid (73). 

A second new synthesis of exo-alkylidene-cycloalkanones involves coupling of the appropriate a-chloronitroalkane with an a-ethoxycarbonylcycloalkanone followed by chloride ion promoted de-ethoxycarbonylation and loss of nitrite ion (Scheme 74). ... 

---