Refernces
10.1016/S0040-4039(00)00753-X
The research focuses on the alkylidenation of esters on solid support and the traceless synthesis of 2-substituted benzofurans. The experiments involve the conversion of polymer-supported esters into enol ethers using a titanocene alkylidene, which is prepared by treating 2-tert-butyldimethylsilyloxybenzaldehyde diphenyldithioacetal with a low valent titanium species, Cp2Ti[P(OEt)3]2. The enol ethers are then treated with acid to release ketones from the Wang resin with high yield. A three-step termination procedure is used to achieve the traceless solid-phase synthesis of 2-substituted benzofurans. The reactants include titanocene dichloride, triethylphosphite, thioacetal, and Wang resin-bound esters, among others. Analytical techniques used to monitor the progress and confirm the completion of reactions include infrared (IR) spectroscopy for carbonyl absorption and weight gain measurements. The study demonstrates a novel alkylidenating agent that enables cyclative termination of solid-phase synthesis without leaving any trace of the attachment site on the solid support, which is beneficial for agrochemical and pharmaceutical research.
10.1016/j.tetlet.2004.10.092
The research aims to develop a novel, mild, and efficient method for synthesizing primary α-amino phosphonates using a one-pot, three-component reaction under solvent-free conditions. The key chemicals used in this study include benzaldehyde, hexamethyldisilazane (HMDS), trialkyl phosphites (such as trimethyl phosphite and triethyl phosphite), and solid lithium perchlorate (LiClO?). The researchers optimized the reaction conditions to achieve high yields and short reaction times, finding that the presence of LiClO? was crucial for the reaction to proceed. The study demonstrated that various aromatic aldehydes and trialkyl phosphites could be successfully converted into primary α-amino phosphonates under these conditions, with yields ranging from 80% to 92%. The mild reaction conditions allowed for the tolerance of sensitive functional groups like OMe and NO?. Additionally, the researchers explored the formation of 1-aryl-N,N'-bis(arylidene)methanediamines using benzaldehyde, HMDS, and LiClO?, obtaining these compounds in high yields with short reaction times. The study concludes that this solvent-free, one-pot synthesis method provides a green and efficient approach for preparing primary α-amino phosphonates, which have significant applications in pharmaceuticals and as enzyme inhibitors.
10.1021/ja01606a062
The study investigates the reaction of sulfenyl chlorides with trialkyl phosphites, resulting in the formation of esters of monothiophosphoric acid. Various alkyl and aromatic sulfenyl chlorides, such as methanesulfenyl chloride, benzenesulfenyl chloride, and p-chloroethanesulfenyl chloride, were reacted with triethyl phosphite, tri-n-propyl phosphite, and tri-n-butyl phosphite. The reactions were rapid, even at Dry Ice temperatures, indicating a nucleophilic displacement of chloride accompanied by the elimination of alkyl chloride. The study also compared the reactivity of these sulfenyl chlorides with that of sulfur monochloride and noted that the sulfenyl chlorides reacted at least as readily as acyl halides, which are known to react exothermally with tertiary phosphites. The compounds synthesized were used for biological testing in cancer chemotherapy studies, with particular interest in the 6-chloro thioester as a potential mustard analog.
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