Refernces
10.1016/S0040-4039(97)01559-1
The research investigates the reactivity of (E)-1-(tert-butyldimethyl)silyloxy-3,3-bis(tributylstannyl)propene (1) as a potential 1,3-dianion equivalent, particularly its selective SE' addition to various aldehydes in the presence of BF3·OEt2. The study aims to explore the synthetic potential of this compound, especially in the context of developing complex natural compounds and (di)enediynes with antitumor properties. Vinylstannane (5h) was converted to vinyl sulfone (10) using sodium bisulfite. The results show high yields of mono-protected diols (5a-h) with exclusive E configuration of the vinyltin residue and good to high syn selectivities, supporting an SE' addition mechanism. Further transformations of these diols into various functionalities, such as acetonides, chloroalcohols, vinyl sulfones, and cross-coupling products, were successfully demonstrated, highlighting the synthetic versatility of the initial adducts. The study concludes that the investigated compound exhibits promising reactivity and selectivity for potential applications in organic synthesis.
10.1002/chem.200400733
The research focuses on the practical synthesis of (+)-biotin from l-cysteine, a significant endeavor due to biotin's crucial role in human nutrition and animal health. The study aims to address the inefficiencies of the existing Goldberg and Sternbach method, which involves over 14 steps, utilizes toxic reagents, and requires impractical diastereomeric or enzymatic resolution. The researchers developed a novel synthetic approach that eliminates the need for bulky protecting groups and reduces the protection-deprotection sequence steps. This method involves the formation of contiguous stereogenic centers through a highly diastereoselective Strecker reaction, a novel ring transformation and deblocking by S,N-carbonyl migration, and the introduction of the carbon chain at C-4 by the Fukuyama coupling reaction. Key chemicals used in the process include l-cysteine, phenyl chloroformate, benzyl bromide, benzyl chloride, sodium bisulfite, sodium cyanide, and various catalysts and reagents for the reactions involved. The conclusions of the research highlight the successful development of a more efficient synthetic method for (+)-biotin, achieved in 10 steps and with an overall yield of 34% from l-cysteine, offering a high yield, ease of operation, and mild reaction conditions.
10.1021/acs.oprd.7b00231
The study presents a novel liquid-liquid extraction method for removing aldehydes and highly reactive ketones from mixtures using sodium bisulfite. The protocol involves dissolving the mixture in a water-miscible organic solvent, adding a saturated sodium bisulfite solution, and then extracting with a water-immiscible organic solvent. The sodium bisulfite reacts with aldehydes to form charged bisulfite adducts, which can be separated from the desired organic components. The study demonstrates that this method is effective for a wide range of aldehydes, including sterically hindered neopentyl aldehydes, and certain ketones, with mild conditions that tolerate various functional groups. The protocol allows for high recovery rates of the desired components and can be scaled up with minimal solvent usage. Additionally, the study explores the recovery of aldehydes by basifying the aqueous layer, achieving high purity and yield. The findings suggest that this extraction protocol can be a valuable tool for chemists dealing with aldehyde and ketone impurities in organic synthesis.
Xn
