A New Samarium Diiodide Induced Reaction: Intramolecular Attack of Ketyl Radical Anions on Aryl Substituents with Formation of 1,4-Cyclohexadiene Derivatives

Abstract

Beware of samarium diiodide and aryl ketones! If the ketyl radical anion which is formed by electron transfer finds a properly placed aryl group, a highly diastereoselective cyclization may occur. After the transfer of a second electron and protonation bi- and polycyclic products with a common 1,4-cyclohexadiene moiety may be isolated [Eq. (a)]. X=CHCO R, NCH Ph; HMPA=(Me N) PO.

Synthesis of Polycyclic Tertiary Carbinamines by Samarium Diiodide Mediated Cyclizations of Indolyl Sulfinyl Imines

“…[1] Many selective and unique transformations are possible [2] and quite a number of naturalproduct syntheses witnesses the usefulness of this electrontransfer reagent. [4] The method proved to be particularly useful in reactions of Nacylated or N-alkylated indolyl ketones of type 3 or 5 that provided tricyclic compounds 4 and 6, respectively. [4] The method proved to be particularly useful in reactions of Nacylated or N-alkylated indolyl ketones of type 3 or 5 that provided tricyclic compounds 4 and 6, respectively.…”

New Samarium Diiodide-Induced Ketyl Couplings - From Analogous Reactions to Serendipitously Discovered Processes

“…With cyclohexanone derivatives such as 91-94 we found again that appropriate relative configuration is a prerequisite for successful reductive cyclization. 22 The like-configured compounds 91-94 smoothly provided the desired tricyclic compounds 95-98 in very good yields. The diastereoselectivities of these cyclizations are also excellent as only the isomers depicted in Scheme 22 are furnished.…”

“…17,29 g-Aryl ketone 59 gave the hexahydronaphthalene derivative 60 in moderate yield though with varying diastereoselectivity for so far unknown reasons. 22,29 It does not seem to be possible to employ unsubstituted phenyl-substituents for cyclizations leading to five-or seven-membered rings. Starting materials 61 and 62 were recovered essentially unchanged.…”

Crystal structure of 2SR,5SR,5aSR,11bSR-5-methyl-1,5,5a,llbtetrahvdro- 2,5-methanonaphtho[2,1-c]oxepin-3(2R)-one, C16H16O2

“…The title compound was obtained by samarium diiodide induced reaction of methyl 2RS-2-( 1 -naphthylmethyl)-4-oxopentanoate in 34% yield (purified by chromatography on silica gel, colourless crystals, mp 453 Κ -455 Κ, recrystallized from hexane/ethyl acetate) [1].…”