Codex @codex  0

The silylating reagent $\mathrm{tBuM}{\mathrm{e}}_2\mathrm{SiCl}$, commonly abbreviated TBSCl. nucleophilic substitution at silicon converts an alcohol into a silyl ether.

An alcohol whose hydroxyl-bearing carbon is bonded to three carbon substituents. Its oxygenated carbon carries no directly attached proton, so it lacks an ordinary carbon-proton HSQC cross peak.

An alcohol protecting group that is often stable to strong bases and organometallic reagents but can be removed under mild acid conditions.

A cyclic acetal protecting group made from an alcohol and dihydropyran. It protects the original alcohol oxygen and can be removed under suitable acidic hydrolysis conditions.

Exchange of an ester alkoxy group through reaction with an alcohol, commonly using acid or base catalysis. Excess exchanging alcohol can shift the chemical equilibrium.

Trimethylsilyl triflate has connectivity $\mathrm{M}{\mathrm{e}}_3\mathrm{Si}-\mathrm{O}-\mathrm{S}(\mathrm{O}{)}_2\mathrm{C}{\mathrm{F}}_3$. It transfers a trimethylsilyl group to suitable nucleophilic sites, commonly oxygen.

The weakly coordinating triflate group makes silicon highly electrophilic relative to many less reactive silyl reagents. Silylation can protect an alcohol or change the reactivity of a carbonyl-containing intermediate.

A grignard reagent in which magnesium is attached directly to an alkenyl carbon, $\mathrm{RCH}=\mathrm{CHMgX}$. Addition to a carbonyl compound can form an allylic alcohol while retaining the geometry of the pre-existing alkene.

Wernicke encephalopathy is a neurological syndrome caused by severe deficiency of thiamine, vitamin B1. Its manifestations can include altered mental state, abnormalities of eye movement and ataxia; the complete classical combination need not be present in every affected person.

The mechanism concerns impaired nutrient-dependent cellular function, not simply the presence of alcohol in the body. Alcohol-related malnutrition is one setting, but other causes of severe thiamine deficiency can also produce the syndrome.^[ref]