3-Chloro-2-(phenylsulfinyl)-1-propene and 3-chloro-2-(phenylsulfonyl)-1-propene: preparation and utility as reagents for .alpha.,.alpha.'-annelation of cyclic ketones

Abstract

The reaction of allyl chloride (7), at -40 °C to -20 °C, with in situ generated phenylsulfenyl chloride (6) affords exclusively the anti-Markovnikov product 1,3-dichloro-2-(phenylthio)propane (8) in 85-90% yield. Oxidation of 8 with 1 equiv of MCPBA to sulfoxide 9 followed by DBU-catalyzed dehydrochlorination yields 3-chloro-2-(phenylsulfinyl)-l-propene (Id) (70%). Treatment of 8 with 2 equiv of MCPBA yields sulfone 10 which is similarly dehydrochlorinated to 3-chloro-2-(phenylsulfonyl)-l-propene (le) (81%). The reaction of pyrrolidine enamines of cyclic ketones with Id and 1.1 equiv of triethylamine in Me2SO at 95-100 °C affords moderate yields of bicyclic keto thioenol ethers, formed via an , '-annelation-Pummérer reaction sequence, together with noncyclized, 2-(phenylsulfinyl)allylated ketone. Similar reactions with le provide good yields of bicyclic keto sulfones as approximate 1:1 mixtures of endo and exo isomers, which may be equilibrated to mixtures containing predominantly the exo compounds by treatment with methanolic sodium methoxide.

Syntheses and properties of carboranylpyrroles

“…The C6-C7 distance, 1.319(4) Å, is typical of a double bond, and the conformation of the carbon chain is such that the C4-C5-C6-C7 torsion angle is near zero, at -1.6(5)°. All seven carbon atoms are approximately coplanar, exhibiting a mean deviation of 0.067 Å. Thioethers 7 were produced in high yields upon addition of in situ generated phenylsulfenyl chloride (from benzenethiol and N-chlorosuccinimide) at low temperature [26]. The reaction was complete in less than 2 h and gave exclusively the antiMarkovnikov product, as determined by NMR spectroscopy and, in the case of 7 (R = Me, n = 1), by X-ray crystallography.…”

Unsymmetrical difunctionalization of cyclooctadiene under continuous flow conditions: expanding the scope of ring opening metathesis polymerization

“…In comparison, when 5-Cl-1-cyclooctene 19 was reacted with MeOH at room temperature for 48 h instead of 4a , no substitution product was detected by LC-MS, supporting our hypothesis of a vicinal SR group assisted substitution process. 13 …”

“…1D : X = SR, Y = Cl). Since the chloride group is easily cleavable through the assistance of the adjacent thioether via neighboring group participation, 13 we envisioned that the 5-Cl,6-SR-COE would be a versatile intermediate to prepare FCOEs with different functionalities ( Fig. 1D : X = SR 1 , Y = OR 2 /NR 2 ).…”

New Synthetic Methods for Hypericum Natural Products

“…More interestingly, Anzeveno and co-workers 33 have reported α,α'-annelation of cyclic ketones using 3-chloro-2-phenylsulfonyl-1-propene as a Michael acceptor. It is noteworthy that it forms the bicyclic skeleton in good yield in one step by treatment of an enamine with a vinylic sulfone (Scheme 31).…”