- A one-pot synthesis of 1,4-dithiins and 1,4-benzodithiins from ketones using the recyclable reagent 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT)
-
A novel access to 1,4-dithiins and 1,4-benzodithiins from the corresponding ketones in one-pot using the recyclable reagent, 1,1′-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) is described. This method is mild, simple, environmentally benign and is
- Murru, Siva,Kavala, Veerababurao,Singh,Patel, Bhisma K.
-
p. 1007 - 1011
(2008/02/04)
-
- Reactions of silica chloride (SiO2Cl)/DMSO, a heterogeneous system for the facile regeneration of carbonyl compounds from thioacetals and ring-expansion annelation of cyclic thioacetals
-
Silica chloride (SiO2Cl)/DMSO, as a heterogeneous system, has been efficiently used for deprotection of thioacetals into aldehydes in dry CH2Cl2 at room temperature. Thioketals without enolizable hydrogens adjacent to a sulfur atom are converted easily to the corresponding ketones in high yields under similar reaction conditions. However, thioketals with enolizable methyl and methylene groups undergo ring-expansion reactions to afford 1,4-dithiepins and 1,4-dithiins in dry CH2Cl2 at room temperature in good yields.
- Firouzabadi, Habib,Iranpoor, Nasser,Hazarkhani, Hassan,Karimi, Babak
-
p. 2572 - 2576
(2007/10/03)
-
- Ring Expansion Reaction of 1,3-Dithiolanes and 1,3-Oxathiolanes Using Tellurium Tetrachloride
-
On treatment with tellurium tetrachloride in dichloromethane at room temperature, 1,3-dithiolanes and 1,3-oxathiolanes undergo smooth ring expansion to give dihydro-1,4-dithiin and dihydro-1,4-oxathiin derivatives respectively in good to moderate yields.
- Tani, Hiroyuki,Inamasu, Tokuo,Tamura, Rui,Suzuki, Hitomi
-
p. 1323 - 1326
(2007/10/02)
-
- Hard Acid and Soft Nucleophile Systems. Part 11. Har-Soft Affinity Inversion: Dehalogenation of α-Halogeno Ketones with Aluminium Chloride and a Thiol
-
α-Halogeno ketones have been dehalogenated with a combination of aluminium chloride and ethanethiol.The mechanism involved in deiodination and debromination differs from that of dechlorination and defluorination.A hard-hard interaction between carbonyl oxygen and aluminium chloride and a soft-soft interaction between iodine or bromine and thiol are the dominant factors for direct deiodination and debromination.In dechlorination and defluorination there is initial formation of the corresponding dithioacetal, whereby hard carbonyl oxygen is replaced by the soft sulphur atom. α-Chloro- and α-fluoro-dithioacetals then undergo dehalogenation to afford vinyl sulphide as a result both of a favourable soft-soft interaction between the sulphur atoms in the dithioacetal entity and thiol, and also a favourable hard-hard interaction between the nucleopilic chlorine or fluorine and aluminium chloride. α-Chloro- and α-fluoro-benzyl benzyl ketones afforded the dehalogenated product with concomitant 1,2-transposition of the carbonyl group.This suggests that there is an indirect path which operates competitively via a 1,2-dithio-olefin from α=halogenodithioacetals to vinyl sulphide.Addition of thiol to vinyl sulphide leads to the final product.A concept of hard-soft affinity inversion is proposed.
- Fuji, Kaoru,Node, Manabu,Kawabata, Takeo,Fujimoto, Mayumi
-
p. 1043 - 1048
(2007/10/02)
-