Camphorsultam, also known as bornanesultam, is a crystalline solid primarily used as a

chiral auxiliary In stereochemistry, a chiral auxiliary is a Stereogenic center, stereogenic group or unit that is temporarily incorporated into an organic compound in order to control the stereochemical outcome of the synthesis. The chirality present in the auxil ...

in the synthesis of other chemicals with a specific desired

stereoselectivity In chemistry, stereoselectivity is the property of a chemical reaction in which a single reactant forms an unequal mixture of stereoisomers during a non- stereospecific creation of a new stereocenter or during a non-stereospecific transformation ...

. Camphorsultam is commercially available in both

enantiomer In chemistry, an enantiomer (Help:IPA/English, /ɪˈnænti.əmər, ɛ-, -oʊ-/ Help:Pronunciation respelling key, ''ih-NAN-tee-ə-mər''), also known as an optical isomer, antipode, or optical antipode, is one of a pair of molecular entities whi ...

s of its ''

exo Exo (; stylized in all caps) is a South Korean-Chinese boy band based in Seoul formed by SM Entertainment in 2011 and debuted in 2012. The group consists of nine members: Xiumin, Suho, Lay Zhang, Lay, Baekhyun, Chen (singer), Chen, Chanyeol, ...

'' forms: (1''R'')-(+)-2,10-camphorsultam and (1''S'')-(−)-2,10-camphorsultam.

Synthesis

Camphorsultam is synthesized by reduction of camphorsulfonylimine. This reaction was originally performed as a

catalytic hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic ...

using

Raney Nickel Raney nickel , also called spongy nickel, is a fine-grained solid composed mostly of nickel derived from a nickel–aluminium alloy. Several grades are known, of which most are gray solids. Some are pyrophoric, but most are used as air-stable s ...

, but the modern preparation instead uses

lithium aluminium hydride Lithium aluminium hydride, commonly abbreviated to LAH, is an inorganic compound with the chemical formula or . It is a white solid, discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthe ...

for the reduction. These reductive methods are

stereoselective In chemistry, stereoselectivity is the property of a chemical reaction in which a single reactant forms an unequal mixture of stereoisomers during a non- stereospecific creation of a new stereocenter or during a non-stereospecific transformation o ...

: although both the ''endo'' and ''exo'' diastereomeric forms are theoretically possible, only the ''exo'' isomer is actually produced due to

steric Steric effects arise from the spatial arrangement of atoms. When atoms come close together there is generally a rise in the energy of the molecule. Steric effects are nonbonding interactions that influence the shape ( conformation) and reactivi ...

effects of one of the

methyl group In organic chemistry, a methyl group is an alkyl derived from methane, containing one carbon atom bonded to three hydrogen atoms, having chemical formula (whereas normal methane has the formula ). In formulas, the group is often abbreviated a ...

s. Camphorsultam is often referred to as ''Oppolzer's sultam'' in reference to Wolfgang Oppolzer and colleagues, who developed the lithium aluminium hydride approach to this compound and pioneered its use in

asymmetric synthesis Enantioselective synthesis, also called asymmetric synthesis, is a form of chemical synthesis. It is defined by IUPAC as "a chemical reaction (or reaction sequence) in which one or more new elements of chirality are formed in a substrate molecul ...

Uses

Due to its ability to form derivatives through its nitrogen atom and the structural rigidity of its chirality, camphorsultam is often used in reactions as a

in order to allow a reaction to proceed with very specific stereoselectivity. During the synthesis of Manzacidin B, camphorsultam is used in order to obtain the desired

product. During a

Michael reaction In organic chemistry, the Michael reaction or Michael 1,4 addition is a reaction between a Michael donor (an enolate or other nucleophile) and a Michael acceptor (usually an α,β-unsaturated carbonyl) to produce a Michael adduct by creating a c ...

, a

Claisen rearrangement The Claisen rearrangement is a powerful carbon–carbon chemical bond, bond-forming chemical reaction discovered by Rainer Ludwig Claisen. The heating of an allyl Vinyl group, vinyl ether will initiate a Sigmatropic reaction, ,3sigmatropic r ...

, or a

cycloaddition reaction In organic chemistry, a cycloaddition is a chemical reaction in which "two or more unsaturated molecules (or parts of the same molecule) combine with the formation of a cyclic adduct in which there is a net reduction of the bond multiplicity". T ...

camphorsultam is able to confer a great deal of stereoselectivity. This allows for more control over the reactions and the creation of very specific desired products. Stereoselectivity can be further increased if substrates are equipped with two chiral auxiliaries, acting in a cooperative fashion. Camphorsultam also has applications in determining a compound's absolute stereochemistry. For that reason, it is sometimes referred to as a "chiral probe".

References

{{reflist Reagents for organic chemistry Sultams Heterocyclic compounds with 3 rings