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The k' pathway implicates a reaction between the doubly charged anion (RCHO 2 2−) and the aldehyde. The direct transfer of hydride ion is evident from the observation that the recovered alcohol does not contain any deuterium attached to the α-carbon when the reaction is performed in the presence of D 2 O.
Fig. 1 shows an example of a diastereoselective CBS reduction being used to prepare a complex macrocyclic alcohol en route to the synthesis of 11-desmethyllaulimalide [22] (an analog of the antitumor agent laulimalide). The authors noted that CBS reduction was much more effective than using either lithium tert-butoxyaluminum hydride or L ...
Sodium hydride is the chemical compound with the empirical formula Na H. This alkali metal hydride is primarily used as a strong yet combustible base in organic synthesis . NaH is a saline (salt-like) hydride , composed of Na + and H − ions, in contrast to molecular hydrides such as borane , silane , germane , ammonia , and methane .
Alcohol oxidation is a collection of oxidation reactions in organic chemistry that convert alcohols to aldehydes, ketones, carboxylic acids, and esters. The reaction mainly applies to primary and secondary alcohols. Secondary alcohols form ketones, while primary alcohols form aldehydes or carboxylic acids. [1] A variety of oxidants can be used.
The alkylphosphonium salt is deprotonated with a strong base such as n-butyllithium: [Ph 3 P + CH 2 R]X − + C 4 H 9 Li → Ph 3 P=CHR + LiX + C 4 H 10. Besides n-butyllithium (n BuLi), other strong bases like sodium and potassium t-butoxide (t BuONa, t BuOK), lithium, sodium and potassium hexamethyldisilazide (LiHMDS, NaHMDS, KHDMS, where HDMS = N(SiMe 3) 2), or sodium hydride (NaH) are also ...
In equatorial attack (shown in blue), the hydride avoids the 1,3-diaxial interaction, but the substrate undergoes unfavorable torsional strain when the newly formed alcohol and added hydrogen atom eclipse each other in the reaction intermediate (as shown in the Newman projection for the axial alcohol).
The hydride adds to an electrophilic center, typically unsaturated carbon. Hydrides such as sodium hydride and potassium hydride are used as strong bases in organic synthesis. The hydride reacts with the weak Bronsted acid releasing H 2. Hydrides such as calcium hydride are used as desiccants, i.e. drying agents, to remove trace water from ...
In practice, considerable sodium is consumed by the formation of hydrogen. [citation needed] For this reason, an excess of sodium is often required. Because the hydrolysis of sodium is rapid, not to mention dangerous, the Bouveault-Blanc reaction requires anhydrous ethanol and can give low yields with insufficiently dry ethanol.