The reaction of β,γ-unsaturated acids with phenylselenenyl chloride.

On the Mechanism of the Selenolactonization Reaction with Selenenyl Halides

“…Chromatographic purification of each of these reaction mixtures yielded only selenolactone 11 and no trace of either 16 or 17 . The yields obtained in entries 3−5 indicate that cyclization of adducts 16 and 17 must have occurred upon exposure to silica gel (vide supra) 2 Reaction of Ester Derivatives of 10 with PhSeCl entryRconversion, a %series 16 , b % 17 , c % 11 , d %yield, e % 1 TMS ( 15b ) 100 b 0 0 100 77 2 TES ( 15c ) 100 c 0 0 100 72 3 TBS ( 15d ) 97 d 6 25 66 73 4 TIPS ( 15e ) 85 e 16 46 23 65 5 TBDPS ( 15f ) 70 f 10 43 17 48 6 f Me ( 15g ) 92 g 52 40 0 7 g t- BuCH 2 ( 15h ) 72 h 32 40 0 a Total conversion of silyl ester starting material into 16 , 17 , and 11 as determined by 1 H NMR.…”

“…From the data presented above, we conclude that the initial step in all selenocyclization reactions with benzeneselenenyl chloride (not just those in which cyclization is slow, e.g., Scheme , eq a) is formation of a β-chloro selenide adduct. Although the inability to purify the β-halo selenide adducts was disappointing, this is perhaps not surprising given the previous unsuccessful attempts to isolate these adducts. ,, …”

“…The reactivity of β,γ-unsaturated acids depends on the alkene substitution pattern. Thus, the expected selenolactonization reaction is competitive with a process of decarboxylative elimination to generate allyl selenides (Scheme , eq c) …”

“…Thus, the expected selenolactonization reaction is competitive with a process of decarboxylative elimination to generate allyl selenides (Scheme 4, eq c). 25 Other than these empirical observations, no studies on the mechanism or the kinetics of these cyclizations are available. In line with our long-term objectives, a clear mechanistic understanding of the reaction would facilitate the development of a viable, catalytic, enantioselective selenocyclization method.…”

Ring‐Opening Regio‐, Diastereo‐, and Enantioselective 1,3‐Chlorochalcogenation of Cyclopropyl Carbaldehydes

“…On the basis of these resultsw ew ere keen to investigate whethers uch asymmetric regioselective 1,3-bisfunctionalizations are also feasible using different substituents.W ec hose sulfenylc hlorides as reactants to add acrosst he CÀCb ond in the cyclopropane; [10,11] because of the highly polarized SÀCl bond we anticipated that sulfur would act as the electrophilic component, with chlorine as the nucleophilic counterpart (Scheme 1, right). [12] To test our notion, achiral meso-cyclopropyl carbaldehyde 1a and p-tolylsulfenyl chloride 2a were chosen as substrates for the optimization.…”