Highly regioselective and stereospecific functionalization of 1,2-propanediol with trimethyl(X)silanes employing the 1,3,2.lambda.5-dioxaphospholane methodology

Abstract

acceptable than triorganotin compounds from toxicological and practical perspectives. Further work on the synthetic scope of this material is in progress. Experimental SectionMaterials. 1,1,1,2,3,3,3-Heptamethyltrisilane,41 cyclohexyl selenide,42 cyclohexyl xanthate,43 neophyl bromide,44 and ditert-butyl hyponitrite45 were prepared following literature procedures. (Me3Si)2Si(D)Me was obtained from the corresponding silyl chloride41 and LiAlD4. All other materials were commercially available and used as received.General Procedure for Reduction of Organic Derivatives (Table I). A solution containing the compound to be reduced, (Me3Si)2Si(H)Me (1.2 equiv), and AIBN (10-20%) as initiator in toluene or benzene was heated at 348-363 K for 0.5-2.5 h and then analyzed by GC. Yields were quantified by GC using dodecane or tetradecane as an internal standard.General Procedure for Kinetic Measurement. tert-Butylbenzene containing a small amount of decane as an internal GC standard was used as solvent. In the case of neophyl bromide, benzene was used as solvent. (Me3Si)2Si(H)Me was added at concentrations between 1.2 and 4 M, and the bromides were added in a ratio of ca. 1:20 respect to the silane. Samples of the reaction mixtures were degassed and sealed under nitrogen in Pyrex am-

Synthesis and Characterization of Tris(trialkylphosphine)copper(I)trimethylsilylchalcogenolates

“… in the 1 H and 13 C{ 1 H} NMR spectra of E(SiMe 3 ) 2 (E = S, Se, Te). A similar trend is also observed for E(Ph)SiMe 3 , as the −SiMe 3 signal in the 1 H NMR spectrum varies from 0.30 ppm to 0.37 ppm to 0.47 ppm on going from S → Se → Te.…”

Mitsunobu and Related Reactions: Advances and Applications

“…The ee of 1,2and 1,3-diols was essentially unaltered during the course of the reaction. A phosphorane (434) mediated pathway, originally suggested by Mathieu-Pelta and Evans, 1343 was proposed for the observed stereo-and regiochemistry. Application of the same reaction conditions to a 1,4-diol led to the exclusive formation of the cyclic ether rather than the azido product.…”

Scalable asymmetric synthesis of a key fragment of Bcl-2/Bcl-xL inhibitors

“…On the other hand, the formation of a phosphorane intermediate could not be ruled out. 25 Next, we embarked on a larger scale synthesis of diamine target 3 by optimizing our validated sequence, with special attention paid to minimize the number of purication procedures initially required at each reaction step (Scheme 6). Subsequent to the easy formation of sulphide 16 on a 2 kilogram scale, the acetal deprotection into aldehyde 8 was performed with H 2 SO 4 , in order to prevent the use of corrosive HCl.…”