Nucleophilic substitution at an sp2 carbon of vinyl halides with an intramolecular thiolate moiety: synthesis of 2-alkylidenethietanes

Base-Controlled Divergent Synthesis of Fluorine-Containing Benzo[4,5]imidazo[2,1-b][1,3]thiazines from 2-Mercaptobenzimidazoles and β-CF3-1,3-Enynes

“…Finally, an intramolecular S N V process takes place to afford the monofluoroalkenemasked cyclic product 4 (Scheme 5B, pathway I). 16 Another reasonable pathway consisting of an ipso-selective S N 2-type defluorothiylation process and a sequential S N 2′-type reaction cannot be ruled out at the present stage (Scheme 5B, pathway II). 14c,17 The remarkable difference in the reaction pathways between DBU and KOH may be attributed to the interaction between the Lewis acidic K cation and the Lewis basic fluorine atom, which facilitates the F-elimination.…”

Recent synthesis of thietanes

“…They obtained 2-phenethyl-4-(propan-2-ylidene)thietane (520) from 5-bromo-6-methyl-1-phenylhept-5-ene-3-thiol (519) as a substrate in 1,3-dimethyl-2-imidazolidinone (DMI) as solvent [25] (Scheme 121). They further applied the method to synthesize 2-phenethyl-4-(propan-2-ylidene)thietane (520) from S-(5-bromo-6-methyl-1phenylhept-5-en-3-yl)thioacetate (521) directly because K 2 CO 3 led to deacetylation of the acetyl group from the thioacetate 521, which was prepared from the corresponding alcohol and thiolacetic acid with the Mitsunobu reagent [153] (Scheme 122). The method was applied using various substrates to synthesize a series of 2-alkylidenethietanes 528-532.…”

“…The method was applied using various substrates to synthesize a series of 2-alkylidenethietanes 528-532. The S-(2,7-dibromoocta-1,7-dien-4-yl)thioacetate (527) generated the 2-methylidenethietane derivative 532 exclusively under the reaction conditions, revealing that the reaction preferred the 4-exo ring closure [153,154] (Scheme 123). In 2009, Li and his co-workers developed a ligand-free CuI-catalyzed intramolecular S-vinylation of 2-bromo/chloroalk-1-ene-4-thiols 533-539 for the preparation of 2-alkylidenethietanes 528, 532, and 540-544.…”