10316-10-6Relevant academic research and scientific papers
DMSO-catalyzed chlorination of alcohols using N-phenylbenzimidoyl chloride
Wang, Qiang,Xu, Jian,Xu, Zhou-Qing,Yan, Ji-Dan
, p. 2071 - 2076 (2013/06/05)
N-phenylbenzimidoyl chloride has been demonstrated as an efficient chlorination reagent catalyzed by dimethyl sulfoxide (DMSO) in conversion of alcohols to corresponding chlorides. The reaction conditions were mild, and most of the substrates gave satisfactory yields. The configuration inversion of the chlorination was proved using optically active phenyl alcohols. The amount of DMSO can be as low as 0.001 eq without reducing the efficiency of the chlorination. A plausible mechanism for the reaction was proposed and proved by experiments. The reaction is stereoselective and potentially chemoselective among primary benzyl alcohols, secondary benzyl alcohols, and unactivated aliphatic alcohols.
Enantioselective synthesis, configurational stability, and reactivity of lithium α-tert-butylsulfonyl carbanion salts
Scholz, Roland,Hellmann, Gunther,Rohs, Susanne,Oezdemir, Diana,Raabe, Gerhard,Vermeeren, Cornelia,Gais, Hans-Joachim
scheme or table, p. 4588 - 4616 (2010/10/21)
The reactions of enantiopure S-tert-butyl sulfones of the type R 1CH(R2)SO2tBu (≥99% ee) with lithiumorganyl compounds gave the corresponding chiral α-sulfonyl carbanion salts [R 1C(R2)SO2tBu]Li with ≥94% ee. The enantioselectivity of the deprotonation of the phenyl- but not dialkyl-substituted sulfones is strongly dependent on the nature of the lithiumorganyl. Because of this observation and the strong decrease in enantioselectivity in the presence of TMEDA and HMPA, we propose an intramolecular proton transfer following complexation of the sulfone by RLi. Racemization of [R1C(R2)-SO2tBu]Li follows first-order kinetics and seems to be mainly an enthalpic process with a small negative activation entropy, as revealed by polarimetric measurements at low temperatures. This is in accordance with Cα-S bond rotation as the rate-determining step. The salts [R1C(R2)SO 2tBu]Li have half-lives of racemization in the order of several hours at -105°C. The deuteriation of the salts at -105°C with CF 3CO2D proceeded with enantioselectivities of 94% ee, the magnitude of which was not significantly affected by the presence of TMEDA and HMPA. The salts also reacted with carbon-based electrophiles at low temperatures with high enantioselectivity. The conversion of R1CH(R 2)SO2tBu via [R1C(R2)SO 2tBu]Li to R1C(R2,E)SO2tBu, which involves the loss of stereogenicity at the α-stereogenic center and its reestablishment upon reaction of the chiral carbanion with electrophiles, occurred with high overall enantioselectivity. Electrophiles attack the anionic C atom of [R1C(R2)SO2tBu]Li with high selectivity on the side syn to the O atoms and anti to the tert-butyl group. The reactivity of the dialkyl-substituted salts [R1C(R 2)SO2tBu]Li (R1, R2 = alkyl) is significantly higher than that of the benzylic salts [RC(Ph)SO2tBu]Li (R = alkyl) and the HMPA-coordinated SIPs of [MeC(Ph)SO2- tBu]Li are significantly more reactive towards EtI than the corresponding O-Li contact ion pairs.
A highly chemoselective and rapid chlorination of benzyl alcohols under neutral conditions
Sun, Lili,Peng, Guisheng,Niu, Hongmei,Wang, Qiang,Li, Chunbao
experimental part, p. 3919 - 3924 (2009/05/26)
A rapid and highly selective chlorination method has been developed using 2,4,6-trichloro-1,3,5-triazine (TCT) catalyzed by dimethyl sulfoxide. The reactions take 10 to 40 minutes, and the yields are almost quantitative. The neutral reaction conditions are compatible with substrates bearing acid-labile functional groups. Both competitive intramolecular and intermolecular reactions for benzyl alcohols in the presence of aliphatic alcohols indicate high selectivity. The procedure has been successfully used in the selective chlorination of gastrodin, a clinically used neuromedicine. This procedure represents a useful new tool in organic and medicinal chemistry. Georg Thieme Verlag Stuttgart.
