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27.15.2.3.3 Variation 3: With Radicals

DOI: 10.1055/sos-SD-027-00519

Yamane, M.; Narasaka, K.Science of Synthesis, (200427629.

O-Substituted oximes and hydrazones are by far the most commonly used radical acceptors among the various C=N functional groups.[‌221‌,‌222‌] Radical addition to the C=N bond of oxime derivatives is more rapid than addition to the C=N bond of imines because the resultant aminyl radicals are stabilized by the unshared electron pair on the adjacent oxygen atom (3-electron bonding interaction). The first radical cyclization involving addition of intramolecular ketyl radicals to the C=N bond of an O-substituted oxime was reported in 1983.[‌95‌] Radical additions to oxime derivatives have been used in a number of total syntheses of natural products.[‌359‌,‌371‌‌375‌] The radical additioncyclization sequence using the oxime part as the radical acceptor has been extensively studied for the preparation of functionalized amine derivatives such as β-amino acids.[‌376‌,‌377‌]Asymmetric synthesis of α-amino acid derivatives (e.g., 46) is achieved by alkyl radical addition to camphorsultam derivatives 45 of glyoxal oxime (Scheme 32).[‌378‌,‌379‌]

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{8eM-[8(M*),8eα,8α,8eβ]}-8-{[(Meeeeeeee)eeeee](eeeeeeeeee)eeeeee}-8,8-eeeeeeeeeeeeeeeee-8e,8-eeeeeee-8,8-eeeeeeeeeeeeeee-8,8-eeeeeee [(M)-88, M8=Me]; Meeeeee Meeeeeeee:[‌888‌]

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