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Chemistry · Glossary

What is Functional-group interconversion?

Definition 28.3 University Chemistry — Year 2 · Chapter 28 — Retrosynthesis and Multistep Strategy

A functional-group interconversion (FGI) is a retrosynthetic step that changes a functional group without changing the carbon skeleton: an alcohol from a ketone (by reduction), an alkane chain from an alkene (by hydrogenation), an amine from an amide.

A retrosynthetic tree for 2-methyl-1-phenylpropan-1-ol. (a) and (b): the two disconnections of the C-C bond next to the alcohol carbon, each an aldehyde and a Grignard reagent. FGI: the alcohol from a ketone, by reduction; (c) the ketone by Friedel–Crafts acylation of benzene. Every arrow reads “is made from”.
A retrosynthetic tree for 2-methyl-1-phenylpropan-1-ol. (a) and (b): the two disconnections of the C−C\ce{C-C} bond next to the alcohol carbon, each an aldehyde and a Grignard reagent. FGI: the alcohol from a ketone, by reduction; (c) the ketone by Friedel–Crafts acylation of benzene. Every arrow reads “is made from”.
SynthonKindSynthetic equivalent
RX−\ce{R-} (alkyl, aryl)donorRMgBr\ce{RMgBr}, RLi\ce{RLi}, RX2CuLi\ce{R2CuLi} (conjugate)
−CH2COR\mathrm{^-CH_2COR}donorthe enolate of CHX3COR\ce{CH3COR}, or ethyl 3-oxobutanoate
−C≡N\mathrm{^-C{\equiv}N}donorNaCN\ce{NaCN}
RC+H−OH\mathrm{R\overset{+}{C}H{-}OH}acceptorthe aldehyde RCHO\ce{RCHO}
RC+=O\mathrm{R\overset{+}{C}{=}O}acceptorthe acyl chloride RCOCl\ce{RCOCl}, an ester
RX+\ce{R+} (primary)acceptorthe halide RBr\ce{RBr} (bimolecular substitution)
+CH2CH2COR\mathrm{^+CH_2CH_2COR}acceptorthe enone CHX2=CHCOR\ce{CH2=CHCOR} (conjugate addition)
Common synthons and their synthetic equivalents. The donor synthons are carbanions, the acceptor synthons carbocations; the real reagents carry the same polarity without the full charge.
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