Satoru Okajima

2,2′-Bis(diarylstibano)-1,1′-binaphthyls (BINASbs); a useful chiral ligand for palladium-catalyzed asymmetric allylic alkylation, and the structure of a BINASbPdCl2 complex

Abstract The first attempt to use enantiopure antimony ligands 1–4 as a chiral auxiliary was successfully accomplished in a palladium-catalyzed asymmetric alkylation of 1,3-diphenylprop-2-ene-1-yl acetate with dimethyl malonate. Under the optimized conditions, the allylation product can be obtained with up to 96% ee in 84% chemical yield by use of enantiopure C2-symmetric 2,2′-bis[di(p-tolyl)stibano]-1,1′-binaphthyl [BINASb(p-Tol)] 4a as a chiral ligand with O-bis(trimethylsilyl)acetamide (BSA) and potassium acetate. The structure of the intermediary BINASb–PdCl2 complex was elucidated by single crystal X-ray analysis, implying that the BINASb should work as a bidentate chiral ligand in the reaction.

Synthesis and resolution of 2,2′-bis[di(p-tolyl)stibano]-1,1′-binaphthyl (BINASb); the first example of an optically active organoantimony ligand for asymmetric synthesis

Abstract Racemic 2,2′-bis[di(p-tolyl)stibano]-1,1′-binaphthyl (BINASb) (±)-2 has been prepared from 2,2′-dibromo-1,1′-binaphthyl 1 via 2,2′-dilithio-1,1′-binaphthyl intermediate, and has been resolved via the separation of a mixture of the diastereomeric Pd complexes 4A and 4B, derived from the reaction of (±)-2 with di-μ-chlorobis{(S)-2-[1-(dimethylamino)ethyl]phenyl-C,N}dipalladium(II) 3. The optically active BINASbs (S)-(+)-2 and (R)-(−)-2 have been shown to be effective chiral ligands for the rhodium-catalyzed asymmetric hydrosilylation of ketones.

New optically active organoantimony (BINASb) and bismuth (BINABi) compounds comprising a 1,1′-binaphthyl core: synthesis and their use in transition metal-catalyzed asymmetric hydrosilylation of ketones

Abstract Racemic 2,2′-bis[diarylstibano]-1,1′-binaphthyls [(±)-BINASbs] and 2,2′-bis[di(p-tolyl)bismuthano]-1,1′-binaphthyl [(±)-BINABi], which are the antimony and bismuth congeners of BINAP, have been prepared from 2,2′-dibromo-1,1′-binaphthyl (DBBN) via 2,2′-dilithio-1,1′-binaphthyl intermediate by treatment with the appropriate metal halides [(p-Tol)2SbBr, Ph2SbBr and (p-Tol)2BiCl]. The optical resolution of the (±)-BINASbs could be achieved via the separation of a mixture of the diastereomeric Pd-complexes derived from the reaction of (±)-BINASbs with di-μ-chlorobis{(S)-2-[1-(dimethylamino)-ethyl]phenyl-C1,N}dipalladium(II). Optically active (R)-BINASb and (R)-BINABi could be also obtained from optically active (R)-DBBN by the same procedure. The enantiopure BINASbs have been shown to be effective chiral ligands for the rhodium-catalyzed asymmetric hydrosilylation of ketones.

Formation of 3H-1,3-benzodiazepines from quinoline N-acylimides

Photolysis of the quinoline N-imides (3) having an electron-donating substituent in the 6- or 8-position affords the corresponding 3H-1,3-benzodiazepines (4), whereas quinolines having an electron-donating group in the other positions or an electron-withdrawing group give no diazepines.

Photolysis of thieno-, furo-, and pyrrolo-[b]pyridine N-imides: formation of 3H-1,3-diazepines

Photolysis of pyridine N-ethoxycarbonylimides condensed with thiophen, furan, and pyrrole rings on the b-side of the pyridine ring affords the corresponding novel 1H-1,2- and 3H-1,3-diazepines, respectively.