Aldol
Topic: Chemistry
From HandWiki - Reading time: 2 min
In organic chemistry, an aldol describes a structural motif consisting of a 3-hydroxy ketone, R–CH(OH)–CHR'–C(=O)–R", or 3-hydroxyaldehyde, R–CH(OH)–CHR'–CH=O. Both are composed of a hydroxy group (–OH) and either a ketone (>C=O) or an aldehyde (–CH=O, which is merely a ketone with a hydrogen substituent). An aldol consisting of a 3-hydroxy ketone is called a β-hydroxy ketone, and an aldol consisting of a 3-hydroxy aldehyde is called a β-hydroxy aldehyde. The term "aldol" may refer to 3-hydroxybutanal.[1][2]
Synthesis and reactions
Aldols are usually the product of aldol addition, i.e. the condensation of two aldehydes.[1] Stereoselective syntheses of aldols is an active area of asymmetric synthesis.
The chemistry of aldols is dominated by one reaction, dehydration:
- RC(O)CH2CH(OH)R' → RC(O)CH=CHR' + H2O
Applications
When two molecules of aldehydes react to form an aldol (β-hydroxy aldehyde), the aldol usually produces secondary compounds since it is unstable.[1] Secondary compounds can be diols, unsaturated aldehydes, or alcohols.[1] The aldol 3-hydroxybutanal is a precursor to quinaldine, a precursor to the dye quinoline Yellow SS.[1]
Aldols are also used as intermediates in the synthesis of natural products and drugs.[3][4] The synthesis of Oseltamivir, an antiviral medicine used to treat the flu, involves the aldol reaction.[5]
The structural motif of aldols is often found in polyketide natural products, which can be used to manufacture antibiotics.[3]
Hydroxypivaldehyde is a rare example of a relatively robust aldol.[6]
See also
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Kohlpainter, Christian; Schulte, Markus; Falbe, Jürgen; Lappe, Peter; Weber, Jürgen; Frey, Guido D. (15 January 2013). "Aldehydes, Aliphatic". Ullmann's Encyclopedia of Industrial Chemistry (7). doi:10.1002/14356007.a01_321.pub3. ISBN 9783527303854. https://onlinelibrary.wiley.com/doi/full/10.1002/14356007.a01_321.pub3?saml_referrer. Retrieved 1 April 2023.
- ↑ PubChem. "CID 21282929" (in en). https://pubchem.ncbi.nlm.nih.gov/compound/21282929.
- ↑ 3.0 3.1 Schetter, Bernd; Mahrwald, Rainer (2006). "Modern aldol methods for the total synthesis of polyketides". Angewandte Chemie International Edition 45 (45): 7506–25. doi:10.1002/anie.200602780. PMID 17103481.
- ↑ Ghosh, Arun K.; Dawson, Zachary L. (2009). "Synthesis of Bioactive Natural Products by Asymmetric syn- and anti-Aldol Reactions". Synthesis 2009 (17): 2992–3002. doi:10.1055/s-0029-1216941. PMID 30443084.
- ↑ Ko, Ji S.; Keum, Ji E.; Ko, Soo Y. (15 October 2010). "A synthesis of oseltamivir (Tamiflu) starting from D-mannitol". J Org Chem 75 (20): 7006–9. doi:10.1021/jo101517g. PMID 20866058. https://pubmed.ncbi.nlm.nih.gov/20866058/.
- ↑ Zhang, Yanping; Mu, Hongliang; Pan, Li; Wang, Xuling; Li, Yuesheng (21 May 2018). "Robust Bulky [P,O] Neutral Nickel Catalysts for Copolymerization of Ethylene with Polar Vinyl Monomers". ACS Catal. 8 (7): 5963–5976. doi:10.1021/acscatal.8b01088.
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