Alkyl bromides synthesis, silver® oxide

Under basic conditions fluorinated carboxylic acids react with alkyl iodides222 or bromides.223 Silver oxide seems to be the base of choice for the synthesis of difluoro(fluorosulfonyl)acetic... 

The first total synthesis of the clerodane alkaloid solidago alcohol was achieved in the laboratory of H.-S. Liu, using a highly diastereoselective DIels-Alder cycloaddition as the key step. The installation of the 3-furyl side chain required the conversion of the bicyclic primary alkyl bromide to the corresponding aldehyde. This was accomplished by the modified Kornblum oxidation, which employed silver tetrafluoroborate to activate the substrate. 

Recently, an intramolecular 1,3-dipolar cycloaddition of transient enantiomerically pure oxa-alkenyl nitrones illustrated a synthesis of enantiomerically pure 3,7-dioxa-2-azabicyclo-[3.3.0]octanes. Treatment of (5)-112 with allyl bromide or cinnamyl chloride in diethyl ether in the presence of silver(I) oxide affords the alkylated esters 173 and 174, respectively. No racemization occurs in this process, as determined by proton nmr. Reduction of the esters with DIBAL at — 72 °C provides the corresponding aldehydes, which are immediately reacted with JV-alkylhydroxylamines in order to minimize racemization. The resulting nitrones 175 cannot be isolated, but undergo spontaneous intramolecular 1,3-dipolar cycloaddition to the enantiomerically pure 3,7-dioxa-2-azabicylo[3.3.0]octanes 176a-d (Scheme 40) [48]. 

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