Search

A base-catalyzed divergent reaction of 3-ylideneoxindoles with O-Boc hydroxycarbamates has been developed to provide efficient access to various amidoacrylates and spiroaziridine oxindoles with generally high yields, which should be potentially useful in drug discovery.

This is the first example of [3 + 2] cycloaddition/ ring contraction sequence under transition-metal-free conditions yielding the title spiro compounds.

The optimized conditions render possible the access to a novel type of phosphorus compounds which may be of pharmaceutical interest.

Aryl addition reactions of ArTi(O-i-Pr)3 to aromatic, heteroaromatic, or α,β-unsaturated ketones are described, producing tertiary alcohols in good to excellent enantioselectivities of up to 97% ee. The structure of the dititanium complex [(i-PrO)2Ti{μ-(S)-BINOLate}(μ-O-i-Pr)TiPh(O-i-Pr)2] [(S)-4] that simultaneously bears a chiral directing ligand and a nucleophile is reported. Complex (S)-4 possesses a pocket structure and has been illustrated as the key active species for addition reactions of both aldehydes and ketones. Mechanistic and stereochemical insights concerning addition reactions of organometallic reagents to organic carbonyls are rationalized based on the pocket structure and pocket size of (S)-4.

The presented approach provides a facile access to a new family of polyfunctionalized spirooxindoles bearing three consecutive stereogenic centers.

Potassium phenoxides (phenoxide, 4-fluorophenoxide, 3-dimethylamino phenoxide) were found to cleave various geminal diacetates and regenerate aldehydes in excellent yields under extremely mild conditions.

A simple method for the introduction of the N-hydroxyurea functionality has been developed. This involves conjugate addition of hydroxylamine to a vinylsulfone substrate. This method was successfully used in a facile synthesis of the 5-lipoxygenase inhibitors, zileuton and A-69412.

An efficient synthesis of des-N-methyl-N-acetyl erythromycin derivatives has been developed, it involves the Polonovsky reaction of erythromycin N-oxide derivatives. The reaction conditions have been established so that the desired products can be prepared in high quality and in good yields. This provides a convenient way to prepare des-N-methyl-N-acetylerythromycin-based macrolides.

A convergent, high yielding, and scalable synthesis of A-79175, with a key step involving a mild and efficient CuPd catalyzed coupling reaction of a terminal acetylene with a substituted 2-iodofuran is discussed.

Asymmetric conjugate additions of activated methyl compounds and primary alcohols to ( R )-(−)-5-[(1 R ,2 S ,5 R )-menthyloxy]-2(5 H )-furanone with high diastereoselectivity are described.

The novel erythromycin A derivatives: 9(S)-9-dihydro-12-O-methylerythromycin A (6) and 12-O-methyerythromycin A (3), have been prepared using a new synthetic approach. The critical step is the regioselective methylation of the 12-hydroxyl of the boron complex of 2', 4''-0-bis(trimethylsilyl)-9(S)-9-dihydroerythromycin A (8), which has unprotected 6-, 9- and 11-hydroxyl groups. The antibacterial activities of these new derivatives were compared with those of erythromycin A (1), clarithromycin (2) and 9(S)-9-dihydroclarithromycin (5).

A new approach for atropselective preparation of axially chiral biaryl was developed. This process proceeded through a chirality transfer from a stereogenic center of a secondary alcohol to the stereogenic axis via regioselective intramolecular silyl group migration. This methodology allowed for the preparation of a single atropisomer 2 in good yield (85%) with high diastereoselectivity (99:1), which subsequently led to the successful development of an efficient asymmetric synthesis of A-240610.0, 1.

2,4-Dichloro-5,5-dimethylhydantoin (DCDMH) was found to be a mild and efficient reagent for the direct oxidative conversion of sulfur compounds to the corresponding arenesulfonyl chlorides in good to excellent yields through oxidative chlorination. The method is suitable for many types of sulfur substrates (thiols, disulfides, and benzylic sulfides). The overall process is simple, practical, and it provides convenient access to a variety of aryl or heteroarylsulfonyl chlorides. The mild reaction conditions and the broad substrate scope render this method attractive and complementary to existing syntheses of aryl or heteroarylsulfonyl chlorides.

An efficient synthesis of various β-enaminoesters has been achieved via Reformatsky reaction with disubstituted formamides as novel electrophiles. The exclusive β-enaminoester E -isomers were obtained in 60–72% yield.