Alkylidene sulfones

Alkoxy-1,2,4,6,8-pentaazanaph thalenes, 431 Alkoxysulfonium fluoroborates, 78 a-Alkylacrylic adds, 301-302 N-Alkylanilines, 439 Alkylaiylacetylenes, 494 Alkylation of ketones, 30,64 2-Alkyl-1,3,2-benzodioxaboroles, 25 Alkylbenzohydroxamates, 389 OAlkylbenzohydroximoyl chlorides, 389 Alkylboronic add esters, 130 4-Alkyl-2-butene-l-ols, 53 2-Alkylcyclopentenones, 484 Alkyldichloroboranes, 130 2-r- Alkyl-1,3,2-dioxaborolanes, 69 Alkylene carbonates, 41 a-Alkylhydracrylic adds, 301-302 2-Alkylidenecydobutanols, 470 Alkylidene sulfones, 61 N-Alkylindoles, 246 Alkyl iodides, 336 Alkylmagnesium fluorides, 260... 

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. ... 

Other electron-withdrawing groups are compatible with diazo transfer and cyclization, Both the / -keto sulfone 9 and the /J-keto phosphonate 11 have been cyclized using rhodium acetate catalysis4 8,49. The cyclized keto phosphonate 12 can be further reacted49 with formaldehyde to yield the a-alkylidene cyclopentanone 13. 

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. 

Nitroalkanes282 288 as well as alkyl sulfones283 288 can serve as useful and general alkyli-dene transfer reagents for highly activated Michael acceptors such as alkylidenemalonic esters (equation 131), Alumina-supported potassium fluoride is an effective reagent for the reaction of nitroalkanes282. The alkylidene transfer from sulfones may be promoted by Ni(acac)2289. 

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. 

Some sulfur-centered functions and a nitro group which are primarily required for stabilizing the anion, are also capable of serving as the leaving group. Thus, sulfonimidoyl-stabilized carbanions, 25, transfer methylene as well as alkylidenes to Michael acceptors (equation 87)" °. Phenyl sulfones (X = S02Ph in equation 85)" and nitromethane... 

Further to investigate this similarity between nitrates and sulfonates, methyl 4,6-0-benzylidene-(and -alkylidene)-a-D-glucoside 2,3-dinitrates were treated with sodium methoxide in methanoP under the conditions used for converting the 2,3-ditosylates into the 2,3-anhydro-a-D-allosides. Much degradation occurred, even at 0°, and a large proportion of nitrite was formed. The only products isolated were the 2- and 3-nitrates of methyl... 

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