Rearrangement unsaturated

S)uithesis Rearrangement Unsaturated sugars Sugar chirons Targeted synthesis... 

Claisen Rearrangements - allyl vinyl ether to an y,5-unsaturated carbonyl... 

Another useful route to cyciopentanes is the ring contraction of 2-bromo-cydohexanones by a Favorskii rearrangement to give csrdopcntanecarboxylic acids. If a 0 dibromoketones are used, ring opening of the intermediate cydopropanone leads selectively to, y-unsaturated carboxylic acids (S.A, Achmad, 1963, 1965 J. Wolinsky, 1965). 

The 5-oxohexanal 27 is prepared by the following three-step procedure (1) 1,2-addition of allylmagnesium bromide to an a, / -unsaturated aldehyde to give the 3-hydroxy-1,5-diene 25, (2) oxy-Cope rearrangement of 25 to give 26, and (3) palladium catalyzed oxidation to afford 27. The method was applied to the synthesis of A -2-octalone (28), which is difficult to prepare by the Robinson annulation[25]. 

The reaction of the vinylcyclopropanedicarboxylate 301 with amines affords an allylic amine via the 7r-allylpalladium complex 302[50]. Similarly, three-membered ring A -tosyl-2-(l,3-butadienyl)aziridine (303) and the four-mem-bered ring azetidine 304 can be rearranged to the five- and six-membered ring unsaturated cyclic amines[183]. 

The Pd(0)-catalyzed rearrangement of the iV-allylenamine 800 in CF3CO2H affords the (5, -unsaturated imine 801, which is hydrolyzed to give the 7, 8-unsaturated aldehyde 802[498]. The vinyloxaspirohexane 803 undergoes rearrangement-ring expansion to give the cyclopentanone 804 in the presence of 1 equiv. of p-nitrophenol[499]. 

Ethynyl carbinols rearrange to conjugated unsaturated aldehydes. Copper or silver salts cataly2e isomeri2ation of the acetate to an aHenic acetate, which can be hydroly2ed to an unsaturated aldehyde (204). 

Unsaturation Value. The reaction temperature, catalyst concentration, and type of counterion of the alkoxide affect the degree of unsaturation. The tendency for rearrangement of PO to aHyl alcohol is greatest with lithium hydroxide and decreases in the following order (100) Li+ >... 

Thermal Cope-type rearrangements between C-vinyl and nitrogen substituents bearing appropriately labeled unsaturation are also known, e.g. (147) -> (148) (67JA60S, 71JOC3076). 

Bergmann s synthesis unsaturated azlactones, 6, 226 Berkelheide rearrangement heterophanes, 7, 777 Berninamycin A, 6, 232 Berninamycinic acid appiications, 6, 709 X-ray diffraction, 6, 669 Betahistine as vasodiiator, 2, 5i9 Betaines... 

CLAISEN - IRELAND Rearrangment Rearrangement ol allyl phenyl ethers to o (or p-)allylphenols or of allyl vinyl ethers to y.S-unsaturated aldehydes or ketones (Claisen) Rearrangement ol allyl esters as enolale anions to y.S-unsaturated acids (Ireland)... 

F E R R I E R Cartx>hydrate Synthesis Synthesis of unsaturated cartx>hydrates by allylic rearrangement. 

MEYER - SCHUSTER Propargyl alcohol rearrangement Add catalyzed rearrangement of acetylenic alcohols into o, -unsaturated carbonyl derivatives... 

Over the years many blends of polyurethanes with other polymers have been prepared. One recent example is the blending of polyurethane intermediates with methyl methacrylate monomer and some unsaturated polyester resin. With a suitable balance of catalysts and initiators, addition and rearrangement reactions occur simultaneously but independently to give interpenetrating polymer networks. The use of the acrylic monomer lowers cost and viscosity whilst blends with 20% (MMA + polyester) have a superior impact strength. 

Cyclic a,) -unsaturated ketones present a rich array of photochemical reactions, some of which are of considerable synthetic value (see Section 6.4 of Part B). For cyclohex-enones, two prominent reactions are the di-rr-methane rearrangement (path A) and the lumiketone rearrangement (path B). 

Dibromo-3-ketones may also be used as substrates for the preparation of A -3-ketones by Joly s method. " Hexamethylphosphoramide has been recommended as a medium suitable for the dehydrobromination of a-bromo ketones to give a, -unsaturated ketones in high yield without rearrange-... 

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