The Robinson annulation is an
organic reactionused to create a six-member ring α,β-unsaturated cyclic ketone, using a ketone(or aldehyde) and methyl vinyl ketone. [Rapson, W. S.; Robinson, R.; "J. Chem. Soc." 1935, 1285.] [Bergmann, E. D.; Gingberg, D.; Pappo, R. "Org. React." 1959, "10", 179. (Review)] [Gawley, R. E. "Synthesis" 1976, 777-794. (Review)] It is named after Sir Robert Robinson, the British chemist who discovered it while he was at the University of Oxford.
In addition to methyl vinyl ketone, 1-chloro-3-butanone [Heathcock, C. H.; Ellis, J. E.; McMurry, J. E.; Coppolino, A. "
Tetrahedron Lett." 1971, "12", 4995.] [Heathcock, C. H.; Mahaim, C.; Schlecht, M. F.; Utawanit, T. " J. Org. Chem." 1984, "49", 3264. (DOI|10.1021/jo00192a004)] and isoxazoles [McMurry, J. E. " Organic Syntheses", Coll. Vol. 6, p.781 (1988); Vol. 53, p.70 (1973). ( [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv6p0781 Article] )] will give the same product.
Wieland-Miescher ketoneis the Robinson annulation product of 2-methyl-1,3-cyclohexanedione and methyl vinyl ketonewhile the Hajos-Parrish ketone is the product of 2-methyl-1,3-cyclopentanedione and methyl vinyl ketone. Asymmetric synthesis of these compounds has greatly increased their synthetic utility [ . Hajos, Z, G.; Parrish, D. R. Asymmetric Synthesis of Optically Active Polycyclic Organic Compunds. German Patent DE 2102623, July 29, 1971.] ["Asymmetric synthesis of bicyclic intermediates of natural product chemistry" Zoltan G. Hajos, David R. Parrish J. Org. Chem.; 1974; 39(12); 1615-1621. DOI|10.1021/jo00925a003] .
Methyl vinyl ketone (or variants thereof) are essential for the
annulationas they are simultaneously a Michael acceptorand able to take part in an aldol condensation. The first step in the Robinson annulation (also spelt annelation) is a Michael addition followed by an aldol reactionas the annulationstep in the process. The reaction then proceeds as an aldol condensation to make the desired cyclohexenonering.
Asymmetric Robinson annulation
organocatalyst Prolinehas been used to resolve the enantiomeric isomers of Robinson annulations in asymmetric synthesis. [" Organic Syntheses", Coll. Vol. 7, p.368 (1990); Vol. 63, p.37 (1985). ( [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv7p0368 Article] )] . A proline derivative was employed in an asymmetric annulation of a geranial["Total Synthesis and Revised Structure of Biyouyanagin" A K. C. Nicolaou, David Sarlah, and David M. Shaw Angew. Chem. Int. Ed.2007, 46, 4708 –4711 DOI|10.1002/anie.200701552] :
The Wichterle reaction is a variant of the Robinson annulation that replaces methyl vinyl ketone with
1,3-dichloro-cis-2-butene. [Wichterle, O. "et al." "Coll. Czech. Chem. Commun." 1948, "13", 300.] [Kobayashi, M.; Matsumoto, T. "Chem. Lett." 1973, 957.] [" Organic Syntheses", Coll. Vol. 5, p.869 (1973); Vol. 45, p.80 (1965). ( [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv5p0869 Article] )]
The reaction sequence in the related Hauser annulation is
michael addition- Dieckman condensation- elimination["Recent Advances in the Hauser Annulation " Mal, D.; Pahari, P. Chem. Rev.; (Review); 2007; 107(5); 1892-1918. DOI|10.1021/cr068398q] . The Hauser donor is an aromatic methylene sulfoxideor sulfonewith a carboxylic estergroup in the ortho position. The Hauser acceptor is also a Michael acceptor. In the original Hauser publication "ethyl 2-carboxybenzyl phenyl sulfoxide" reacts with 3-pentene-2-onewith LDAas a base in THF at -78°C ["New synthetic methods for the regioselective annelation of aromatic rings: 1-hydroxy-2,3-disubstituted naphthalenes and 1,4-dihydroxy-2,3-disubstituted naphthalenes"Frank M. Hauser and Richard P.Rhee J. Org. Chem.; 1978; 43(1) pp 178 - 180; DOI|10.1021/jo00395a048] :
The original reaction product still contains the sulfoxide group but it is lost on heating in an elimination reaction. The ultimate reaction product is a
napthalenederivative. The dual purpose of the sulfoxide group is as stabilizing group for the carbanionin the first reaction step and as leaving groupin the second.
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