18668-72-9Relevant articles and documents
A mild method for the replacement of a hydroxyl group by halogen: 3. the dichotomous behavior of α-haloenamines towards allylic and propargylic alcohols
Munyemana, Fran?ois,Patiny, Luc,Ghosez, Léon
, (2021/06/07)
A study of the deoxyhalogenation of allylic and propargylic alcohols with tetramethyl-α-halo-enamines is reported. Primary allylic and primary and secondary propargylic alcohols gave the corresponding halides in high yields. Secondary allylic and propargylic alcohols yielded the corresponding secondary halides but the reaction also produced some rearranged primary halides (I > Br > Cl). The reactions with tertiary allylic and tertiary propargylic alcohols gave several products and was therefore of little synthetic value. However, the addition of triethylamine to the reaction mixture or the use of lithium alkoxide instead of alcohol brought about a major change of the course of the reaction which led to amides carrying an allyl or an allenyl group at C2. This was shown to result from a Claisen-Eschenmoser rearrangement of an intermediate α-allyloxy- or propargyloxy-enamine.
Phase-Vanishing Methodology for Efficient Bromination, Alkylation, Epoxidation, and Oxidation Reactions of Organic Substrates
Jana, Nirmal K.,Verkade, John G.
, p. 3787 - 3790 (2007/10/03)
(Matrix presented) In cases where both reactants in a phase-vanishing reaction are less dense than the fluorous phase, an alternative to the U-tube method is to employ a solvent with greater density than the fluorous phase, such as 1,2-dibromoethane. This modification has been successfully applied to the methylation of a phenol derivative with dimethyl sulfate and to the m-CPBA-induced epoxidation of alkenes, N-oxide formation from nitrogen-containing compounds, and S-oxide or sulfone formation from organic sulfides.
Stereoselective thermal rearrangement of syn-7-(1,2-Butadienyl)-1-methylbicyclo[2.2.1]hept-2-ene [syn-7-(3-Methylallenyl)-1-methylnorbornene]
Duncan, James A.,Hendricks, Robert T.,Kwong, Katy S.
, p. 8433 - 8442 (2007/10/02)
The synthesis and separate thermal rearrangements of (±)-(1R*,4S*,7S*)-7-[(R*)-1,2-butadienyl]-1- methylbicyclo[2.2.1]hept-2-ene (8a) and (±)-(1R*,4S*,7S*)-7-[(S*)-1,2-butadienyl]-1- methylbicyclo[2.2.1]hept-2-ene (8b) are described. Both 8a and 8b are shown to rearrange to (±)-cis-1-ethylidene-3a,4,5,7a-tetrahydro-6-methylindene (9) and (±)-cis-1-ethylindene-3a,4,5,7a-tetrahydro-3a-methylindene (10) with greater than 90% stereoselectivity. Epimer 8a gives predominantly (E)-9 and (Z)-10, whereas 8b gives predominantly (Z)-9 and (E)-10, results consistent with either a six-electron [σ2s + π2s + π2s] Cope or eight-electron [σ2s + π2s + (π2s + π2a)] augmented Cope process. Stereochemical assignments (8a vs 8b, (E)-9 vs (Z)-9, and (E)-10 vs (Z)-10) are based upon experiments in nuclear Overhauser effect (NOE) difference spectroscopy.
