16192-33-9Relevant academic research and scientific papers
REACTIONS OF SODIUM CYANOBOROHYDRIDE WITH BENZOTHIAZOLIUM AND Δ2-THIAZOLINIUM CATIONS. FORMATION OF BENZOTHIAZOLINES, THIAZOLIDINES AND STABLE THIAZABOROLES
Singh, Harjit,Rakesh, Sarin,Singh, Kamaljit,Contreras, Rosalinda,Uribe, Guillermo
, p. 5193 - 5202 (1989)
Sodium cyanoborohydride reduction of benzothiazolium 1 and Δ2-thiazolinium 2 cations give benzothiazolines 3 and thiazolidines 5 alongwith thio>boranecarbonitriles(N-B) 4 and 6.Because
N-Methyl-Benzothiazolium Salts as Carbon Lewis Acids for Si?H σ-Bond Activation and Catalytic (De)hydrosilylation
Fasano, Valerio,Radcliffe, James E.,Curless, Liam D.,Ingleson, Michael J.
, p. 187 - 193 (2017/01/09)
N?Me-Benzothiazolium salts are introduced as a new family of Lewis acids able to activate Si?H σ bonds. These carbon-centred Lewis acids were demonstrated to have comparable Lewis acidity towards hydride as found for the triarylboranes widely used in Si?H σ-bond activation. However, they display low Lewis acidity towards hard Lewis bases such as Et3PO and H2O in contrast to triarylboranes. The N?Me-benzothiazolium salts are effective catalysts for a range of hydrosilylation and dehydrosilylation reactions. Judicious selection of the C2 aryl substituent in these cations enables tuning of the steric and electronic environment around the electrophilic centre to generate more active catalysts. Finally, related benzoxazolium and benzimidazolium salts were found also to be active for Si?H bond activation and as catalysts for the hydrosilylation of imines.
Nonacidic and Highly Chemoselective Protection of the Carbonyl Function. 3-Methylbenzothiazolines as a Base- and Acid-Resistant Protected Form for the Carbonyl Groups
Chikashita, Hidenori,Komazawa, Shun-ichiro,Ishimoto, Nishiki,Inoue, Koji,Itoh, Kazuyoshi
, p. 1215 - 1225 (2007/10/02)
A simple and useful new type of protection method for carbonyl groups by conversion into 3-methylbenzothiazoline derivatives with o-(methylamino)benzenethiol was describe.With this method, 3-methylbenzothiazolines were conveniently obtained in excellent yields from various aldehydes and ketones.This method allows efficient protection and deprotection under mild and neutral conditions and affords protection of the carbonyl group against both basic and acidic conditions.The difference in reactivity between different carbonyl groups was successfully utilized for the chemoselective benzothiazolination of the formyl group of 4-oxopentanal and also for the chemoselective conversion of 4-androstene-3,17-dione and progesteron into the corresponding benzothiazolines with the nonconjugated keto groups remaining intact. 2-Substituted benzothiazolines derived from aldehydes were efficiently converted into 2,2-disubstituted benzothiazolines via alkylation, with a varity of Grignard or organolithium reagents, of 2-substituted 3-methylbenzothiazolium salts which were readily obtained by the treatment of the former thiazolines with trityl perchlorate in acetonitrile.These salts were also obtained in good yields from aldehydes in one-pot syntheses by the treatment with o-(methylamino)benzenethiol in acetonitrile followed by addition of trityl perchlorate. 3-Methylbenzothiazolium iodide was found to be also effective as a formyl cation equivalent and the reactions with Grignard or organolithium reagents produced the corresponding 2-substituted benzothiazolines in good yields.With this reaction, 2-deutero-3-methylbenzothiazolium iodide was effectively applied as a deuterated formyl cation equivalent for the synthesis of aldehyde-d.
Carbon Transfer Reactions with Heterocycles: Part II - Carbon Transfer Reactions of Thiazolidines and Benzothiazolines
Singh, Harjit,Sarin, Rakesh,Singh, Kamaljit
, p. 132 - 134 (2007/10/02)
Thiazolidines (2) and benzothiazolines (3) transfer their C-2 unit at carbonyl group oxidation level to nucleophiles but reactions of 3 are attended by oxidation to benzothiazoles.
3-METHYLBENZOTHIAZOLINES AS A NEW PROTECTED FORM FOR THE CARBONYL FUNCTION
Chikashita, Hidenori,Ishimoto, Nishiki,Komazawa, Shunichiro,Itoh, Kazuyoshi
, p. 2509 - 2514 (2007/10/02)
Protection of carbonyl groups with N-methyl-o-aminothiophenol in ethanol under neutral conditions gave the corresponding benzothiazoline derivatives which were stable against basis, acidic and other reaction conditions.Removal of the protecting group was
Alkylation of Benzothiazolines and the Stevens Rearrangement of the Resulting 2,3,3-Trisubstituted Benzothiazolinium Salts
Akiba, Kin-ya,Ohara, Yoshio,Inamoto, Naoki
, p. 2976 - 2983 (2007/10/02)
Alkylation of 2-substituted 3-methyl- or 3-ethylbenzothiazolines with Meerwein reagents gave 2-substituted 3,3-dialkylbenzothiazolinium tetrafluoroborates (3).The configuration of two alkyl groups on the nitrogen was assigned by NMR spectra and NOE measurement.In the Stevens rearrangement of 3 with lithium diisopropylamide ethyl group showed a much larger migratory aptitude (Et:Me>20:1) than methyl group irrespective of the configuration of 3, and cyclic ammonium ylide with planar ?-type carbanion was proposed as an intermediate. 3 suffered nucleophilic attack at the ring sulfur atom by butyllithium to afford a ring-opened ammonium ylide, which collapses to a radical pair to give unusual Stevens rearrangement product, where o-alkylthiophenyl group migrated selectively in preference to alkyl group, because of stabilization by participation of o-alkylthio group.
