Pregled bibliografske jedinice broj: 1133842
A NEW SEQUENTIAL METHOD FOR THE HYDROLYSIS OF ALLYL ETHERS INDUCED BY A "GREEN" CATALYST: A NEW STRATEGY FOR ALCOHOL DEPROTECTION.
A NEW SEQUENTIAL METHOD FOR THE HYDROLYSIS OF ALLYL ETHERS INDUCED BY A "GREEN" CATALYST: A NEW STRATEGY FOR ALCOHOL DEPROTECTION. // 13. Europski simpozij iz organske kemije (ESOC 13)
Cavtat, Hrvatska, 2004. str. P1-60 (poster, međunarodna recenzija, sažetak, znanstveni)
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Naslov
A NEW SEQUENTIAL METHOD FOR THE HYDROLYSIS OF ALLYL ETHERS INDUCED BY A "GREEN" CATALYST: A NEW STRATEGY FOR ALCOHOL DEPROTECTION.
Autori
Dean Marković, Pierre Vogel
Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni
Izvornik
13. Europski simpozij iz organske kemije (ESOC 13)
/ - , 2004, P1-60
Skup
13thEuropean Symposium of Organic Chemistry
Mjesto i datum
Cavtat, Hrvatska, 10.09.2003. - 15.09.2003
Vrsta sudjelovanja
Poster
Vrsta recenzije
Međunarodna recenzija
Ključne riječi
SO2, radical, ether deprotection, cleavage, allyl, methallyl, prenyl, methylprenyl
Sažetak
Polysulfones ( copolymers of alkene and S02) are capable to isomerize alkenes. The process implies the formation of an initial allyl radical, formed by a chain-process involving the hydrogen transfer between the alkene and the intermediate allyl radical. The formation of the latter intermediate is two steep process in which a RSO2 radical abstracts first an electron from the alkene with formation of an radical cation. In the second steep the latter loses a proton with formation of an allyl radical. Accordingly, the rate of the polysulfone catalysed alkene isomerization depends strongly uopon its ionisation potential. This fact has been used to invent a new strategy for alcohol, aldehyde, ketone and hemiacetal protections. While allyl ethers are not isomerised with polysulfone, methallyl ethers are isomerised into the corresponding enol ethers (and then hydrolysed) on heating with polysulfone catalyst. Prenyl ethers and methylprenyl ethers are isomerised much faster. A polyol protected as allyl, methallyl and methylprenyl ethers will be deprotected under neutral conditions by the polysulfone with the following reaction sequence: methylprenyl> prenyl>> methallyl>> allyl (not reactive). Under our conditions (neat + polysulfone catalysts ; or octane ; or CH2Cl2 solution + polysulfone catalyst) sillyl and benzyl as well as esters were not hydrolyzed. The method has been applied to the protection of aldehydes and ketones as isoprenylketals. The later are deprotected by our polysulfone under neutral conditions!
Izvorni jezik
Engleski
Znanstvena područja
Kemija
