667-20-9Relevant academic research and scientific papers
Controllable, Sequential, and Stereoselective C-H Allylic Alkylation of Alkenes
Qin, Ling,Sharique, Mohammed,Tambar, Uttam K.
supporting information, p. 17305 - 17313 (2019/11/03)
The direct conversion of C-H bonds into new C-C bonds represents a powerful approach to generate complex molecules from simple starting materials. However, a general and controllable method for the sequential conversion of a methyl group into a fully substituted carbon center remains a challenge. We report a new method for the selective and sequential replacement of three C-H bonds at the allylic position of propylene and other simple terminal alkenes with different carbon groups derived from Grignard reagents. A copper catalyst and electron-rich biaryl phosphine ligand facilitate the formation of allylic alkylation products in high branch selectivity. We also present conditions for the generation of enantioenriched allylic alkylation products in the presence of catalytic copper and a chiral phosphine ligand. With this approach, diverse and complex products with substituted carbon centers can be generated from simple and abundant feedstock chemicals.
Copper-Catalyzed Aminothiolation of 1,3-Dienes via a Dihydrothiazine Intermediate
Sleet, Christopher E.,Tambar, Uttam K.
supporting information, p. 5536 - 5540 (2017/05/05)
Heteroatom-containing organic molecules are of particular interest to medicinal chemists and materials scientists. A strategy to reach these architectures via direct difunctionalization of abundant 1,3-dienes is especially attractive. Herein, we describe the development of a regio- and diastereoselective 1,4-aminothiolation of 1,3-dienes with a sulfur diimide reagent, a copper catalyst, and alkyl Grignard reagents. This unique protocol provides remote nitrogen and sulfur functionalities with high levels of stereocontrol. The reaction proceeds via a tandem hetero-Diels–Alder cycloaddition of N,N′-bis(benzenesulfonyl)sulfur diimide with 1,3-diene followed by copper-catalyzed Grignard substitution. Mechanistic studies support a copper catalyzed formation of an unprecedented [10-S-4] sulfurane that reductively eliminates to afford a 3,6-dihydrothiazine, which is selectively converted to 1,4-aminothiols.
Allylic functionalization of unactivated olefins with grignard reagents
Bao, Hongli,Bayeh, Liela,Tambar, Uttam K.
supporting information, p. 1664 - 1668 (2014/03/21)
New advances in the functionalization of unactivated olefins with carbon nucleophiles have provided more efficient and practical approaches to convert inexpensive starting materials into valuable products. Recent examples have been reported with stabilized carbon nucleophiles, tethered carbon nucleophiles, diazoesters, and trifluoromethane donors. A general method for functionalizing olefins with aromatic, aliphatic, and vinyl Grignard reagents was developed. In a one-pot process, olefins are oxidized by a commercially available reagent to allylic electrophiles, which undergo selective copper-catalyzed allylic alkylation with Grignard reagents. Products are formed in high yield and with high regioselectivity. This was utilized to synthesize a series of skipped dienes, a class of compounds that are prevalent in natural products and are difficult to synthesize by known allylic alkylation methods. It all begins with olefins: Allylic functionalization with carbon nucleophiles is a powerful strategy for converting unactivated olefins into complex products. A general method for functionalizing olefins with aromatic, aliphatic, and vinyl Grignard reagents was developed. In a one-pot process, olefins are oxidized by a commercially available reagent to allylic electrophiles, which undergo selective copper-catalyzed allylic alkylation with Grignard reagents. Copyright
Catalytic enantioselective allylic amination of olefins for the synthesis of ent -sitagliptin
Bao, Hongli,Bayeh, Liela,Tambar, Uttam
supporting information, p. 2459 - 2463 (2013/11/06)
The presence of nitrogen atoms in most chiral pharmaceutical drugs has motivated the development of numerous strategies for the synthesis of enantiomerically enriched amines. Current methods are based on multistep transformations of functionalized allylic electrophiles to form chiral allylic amines. The enantioselective allylic amination of nonactivated olefins would represent a more direct and more attractive strategy. We report the enantio selective synthesis of ent-sitagliptin through an allylic amination of a nonactivated terminal olefin. Georg Thieme Verlag Stuttgart, New York.
Catalytic enantioselective allylic amination of unactivated terminal olefins via an Ene reaction/[2,3]-rearrangement
Bao, Hongli,Tambar, Uttam K.
supporting information, p. 18495 - 18498 (2013/01/15)
The enantioselective allylic amination of unactivated terminal olefins represents a direct and attractive strategy for the synthesis of enantioenriched amines. We have developed the first use of a nitrogen-containing reagent and a chiral palladium catalyst to convert unfunctionalized olefins into enantioenriched allylic amines via an ene reaction/[2,3]-rearrangement.
DERIVATIVES OF SULFOXYLIC DIAMIDE
Pel'kis, N. P.,Levchenko, E. S.
, p. 1963 - 1967 (2007/10/02)
N,N'-Disubstituted sulfur diimides are reduced by the action of thiophenols to N,N'-disubstituted sulfoxylic diamides R1NHSNHR2.Compounds where R1 = R2 = SO2Ar, COPh enter readily into reaction both with retention and with cleavage of the S-N bond.In reaction with secondary amines and CH acids they are "carriers of sulfur." 2,5-Diaroyl-1,2,5-thiadiazolidine-3,4-diones are formed by the successive action of trimethylchlorosilane and oxalyl chloride on the compounds where R1 = R2 = COPh, COC6H4Cl-p.
N,N'-DIACYLSELENIUM DIIMIDES III. NEW METHODS OF SYNTHESIS
Derkach, N. Ya.,Barashenkov, G. G.,Levchenko, E. S.
, p. 837 - 839 (2007/10/02)
In the reaction of selenyl fluoride or chloride with N,N-bis(trimethylsilyl)sulfonamides N,N'-diacylselenium diimides (RSO2N=)2Se were obtained.Selenium diimides are also formed in the reaction of difluoroselenimides RSO2N=SeF2 with hexamethyldisiloxane.The difluoroselenimides were obtained by the reactions of selenium tetrafluoride with disilylated amides in a molar ratio of 1:1.
