A novel rearrangement leading to methoxycarbonylmethylated silyl enol ethers

Methyl 2-siloxycyclopropanecarboxylates rearrange smoothly and quantitatively to the corresponding silyl enol ethers (3) by addition of a catalytical amount of iodo trimethylsilane. Scope and limitation of this novel process as well as the synthesis of the electron rich diene (10a) are described.     

Gold-catalyzed rearrangement of substituted allyl aryl ethers

Triphenylphosphinegold(I) complexes catalyze the Claisen-type rearrangement of aryl allyl ethers to the corresponding branched and linear products. The product distribution depends on the olefin geometry of the allylic ether. Stereochemical transfer experiments support an ionic mechanism.     

Spiroketals via oxidative rearrangement of enol ethers

Oxidative rearrangement of cyclic enol ethers leads to alpha-alkoxyesters. In the presence of a neighboring spiroether, this approach provides a stereoselective access to spiroketals. A modified proposal for the biosynthesis of acutumine is presented.     

Cyclic glycol ethers derived from dialkylstannanediols

The splitting of polydialkylstannoxanes (R₂SnO)(inm) is studied by 1,2-, 1,3-, 1,4-, 1,5-, and 1,6-glycols. In this way ten glycol ethers of dialkylstannanediols, mainly with 5,6, or 10-membered rings, are obtained, eight of which were previously unknown.     

Synthesis of mercaptals

Summary The diethyl mercaptals of cinnamaldehyde, 5-phenyl-2,4-pentadienal, citral, and -cyclocitral were synthesized and characterized.     

Low-temperature n-butyllithium-induced rearrangement of allyl 1,1-dichlorovinyl ethers

[reaction: see text]. Upon treatment with n-BuLi at low temperatures, a variety of allyl 1,1-dichlorovinyl ethers 2 undergo rearrangement to furnish gamma,delta-unsaturated esters 3 after alcohol addition. Compounds containing quaternary centers (3e: R1 = H, R2, R3 = -(CH2)5-; 3f: R1 = H, R2 = CH3, R3 = (CH2)2CH(CH3)2) may be formed in high yield and under mild conditions utilizing this protocol. The reaction is stereospecific and may be applied to the preparation of Delta(2,3)-beta-C-glycosides and alpha,beta-disubstituted lactones.     

Smiles rearrangement of polyfluoro substituted 2-acetylaminodiaryl ethers

Polyfluoro substituted 2-acetylaminodiaryl ethers of the type Ar_FOC₆H₄NHAc-o (II) that contain in the fluorinated ring an acceptor group, like analogs of the NH₂ group, undergo on heating in DMF the Smiles rearrangement accompanied by partial migration of the acetyl group and cyclization (in case of ethers (IIa, b)) to phenoxazine derivatives. In the case of heating in DMF, the rate constant of the rearrangement of diphenyl ether (IIa) is by an order of magnitude lower than the rate constant of the rearrangement of its analog with an NH₂ group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 850–854, April, 1990.     

The production of organic nitrates from atmospheric oxidation of ethers and glycol ethers

The production of organic nitrates from OH reaction (in the presence of NO) with methoxy propane, 1‐methoxy‐2‐propanol, ethoxy butane, and 2‐butoxyethanol was studied. The measured total organic nitrate yields were 1.8 (±0.4)%, 0.98 (±0.2)%, 7.7 (±2)%, and 9.6 (±1)%, respectively. The total organic nitrate yield for methoxypropane is 26% of that (7.0%) for n‐butane. The organic nitrate yield for ethoxy butane is 55% of that (14%) for n‐hexane. The peroxy radicals produced from OH reaction with the methylene groups α to the ether linkage have an organic nitrate branching ratio (k_3b/k₃) value ∼50% of those in analogous n‐alkanes. On the other hand, k_3b/k₃ values for peroxy radical functional groups not adjacent to the ether linkage (in γ and δ positions) are on average 1.7 times greater than for the analogous n‐alkyl peroxy radicals. The organic nitrate formation yield for 1‐methoxy‐2‐propanol is almost half that of methoxy propane, while for 2‐butoxyethanol it is 21% greater than that of butoxyethane. Our data lead us to the conclusion that the ether linkage imparts an inductive effect that decreases the value of k_3b/k₃ for peroxy radicals adjacent to it, yet has a stabilizing effect, from the additional vibrational modes for those peroxy radicals not adjacent to it, increasing their k_3b/k₃ values. The effect of both the  O and OH groups in these molecules and the importance of their position relative to the peroxy group are discussed in this paper. © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 686–699, 2005     

Synthesis of alkynyl ethers and low-temperature sigmatropic rearrangement of allyl and benzyl alkynyl ethers

Alpha-alkoxy ketones 3 can be transformed into 1-alkynyl ethers 5 by a two-step procedure involving formation of the enol triflate or phosphate and base-induced elimination. Performing the same reaction sequence with allylic alcohols (R2OH, R2 = allyl) furnishes instead gamma,delta-unsaturated carboxylic acid derivatives 6, derived from [3,3]-sigmatropic rearrangement of the intermediate allyl alkynyl ethers at -78 degrees C and trapping of the subsequently formed ketene with nucleophiles (Nu-H). Benzyl alkynyl ether 5 (R2 = benzyl) rearranges to indanone 7 upon heating to 60 degrees C.     

Synthesis and rearrangement of phenyl ethers of 5,6-dihydropyrans

4-Methyl-5-phenoxy-5,6-dihydropyrans were synthesized by the reaction of 3,4-dibromo-4-methyltetrahydropyran with a number of substituted phenols. The products are converted to the corresponding phenols under the conditions of the Claisen rearrangement.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 315–317, March, 1985.     

[1,2]-Wittig rearrangement from chloromethyl ethers

The reaction of different chloromethyl ethers 1 with an excess of lithium powder and a catalytic amount of 4,4′-di-tert-butylbiphenyl (2.5 mol %) in THF at 0 °C leads to the corresponding α-lithiomethyl ether intermediates, through a chlorine-lithium exchange, which spontaneously undergo a clean [1,2]-Wittig rearrangement affording the expected homobenzylic alcohols 2. This is the first version of this rearrangement starting from easily available chloromethyl ethers.     

Lewis acid mediated claisen-type rearrangement of aryl dienyl ethers

In the presence of BF₃·.OEt₂, aryl dienyl ethers were rearranged under mild conditions to afford dienyl phenols in good yields.     

Bismuth triflate catalyzed Claisen rearrangement of allyl naphthyl ethers

Bismuth triflate was found to be an efficient catalyst for the Claisen rearrangement of allyl naphthyl ethers. The reaction proceeds smoothly with a catalytic amount of bismuth triflate (20 mol %) to afford the corresponding ortho-allyl naphthol in moderate to good yields in most cases.