Stereodivergent Zweifel Olefination and its Mechanistic Dichotomy.

Stereoselective Zweifel olefination using boronate complexes carrying two different reactive π-systems was achieved to synthesize vinyl heteroarenes and conjugated 1,3-dienes in good yield and up to 100 % stereoselectivity, which remains unexplored until now. Most importantly, we report the unprecedented formation of E vs. Z-vinyl heteroarenes for different heteroarenes under identical conditions. Density functional theory (DFT) investigations unveil the mechanistic dichotomy between olefin and heteroarene activation followed by 1,2-migration, leading to E or Z-vinyl heteroarenes respectively. We also report a previously unknown reversal of stereoselectivity by using 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as an electrophile. The Zweifel olefination using a boronate complex that carries two different olefins was previously unexplored due to significant challenges associated with the site-selective activation of olefins. We have solved this problem and reported the site-selective activation of olefins for the stereoselective synthesis of 1,3-dienes.

One pot conversion of phenols and anilines to aldehydes and ketones exploiting α gem boryl carbanions.

Functional group interconversion is an important asset in organic synthesis. Phenols/anilines being naturally abundant and the carbonyl being the most common in a wide range of bioactive molecules, an efficient conversion is of prime interest. The reported methods require transition metal catalyzed cross coupling which limits its applicability. Here we have described a method for synthesizing various aldehydes and ketones, starting from phenol and protected anilines via Csp2-O/N bond cleavage in a one-pot/stepwise manner. Our synthetic method is found to be compatible with a diverse range of phenols and anilines carrying sensitive functional groups including halides, esters, ketal, hydroxyl, alkenes, and terminal alkynes as well as the substitution on the aryl cores. A short-step synthesis of bioactive molecules and their functionalization have been executed. Starting from BINOL, a photocatalyst has been designed. Here, we have developed a transition metal-free protocol for the conversion of phenols and anilines to aldehydes and ketones.

Reactivity of 1,3-enyne MIDA boronates: exploration of novel 1,2-alkyne shift via gem-difluorination.

The discovery of a new class of heteroatom-rich boron-containing molecules (BCMs) and iterative cross-coupling (ICC) partners created a toolbox for future drug developments using organoboron compounds. Herein, we report the potential utility of 1,3-enyne MIDA boronates to access diverse gem-difluoro MIDA boronates via novel 1,2-alkyne shift. This unique reactivity of 1,3-enyne MIDA boronates offers facile access to previously challenging ß-difluorinated alkyl borons. Furthermore, we demonstrated the synthesis of various novel furan-based BCMs via 5-endo-dig cyclization and iterative coupling partners via copper-catalyzed hydroboration and platinum-catalyzed diboration reaction.

Recent advances in the synthesis and reactivity of MIDA boronates.

Organoboron compounds have a wide-range of applications in synthetic methodologies, natural products, and bioactive molecule synthesis. The sensitivity of boronic acid toward most synthetic reagents makes it necessary to introduce a protecting group before its utilization. Benchtop stable MIDA boronates have been found compatible with various common synthetic reagents which opens the doors for the synthesis of various small building blocks, natural products, and bioactive compounds. MIDA boronate compounds have been extensively utilized in Suzuki Miyaura coupling and Iterative cross-coupling reactions for the total synthesis of bioactive molecules and polymerization reactions. Different MIDA boronate compounds like vinyl, acyl, formyl, acrylic, and α-carbonyl MIDA boronates also act as novel synthetic building blocks for various synthetic transformations in organic synthesis. This paper summarizes the importance of MIDA boronate compounds in various aspects of organic chemistry.