The Simmons-Smith reaction is an organic reaction in which a carbenoid reacts with an alkene (or alkyne) to form a cyclopropane.[1][2][3] It is named after Howard Ensign Simmons, Jr. and R. D. Smith.
Thus, cyclohexene, diiodomethane, and a zinc-copper couple (as iodomethylzinc iodide, ICH2ZnI) yield norcarane (bicyclo[4.1.0]heptane).[4][5]
Alternatively, diethylzinc is used instead of the zinc-copper couple.
The Simmons-Smith reaction is generally subject to steric effects, and thus cyclopropanation usually takes place on the less hindered face.[6][7] However, when hydroxy substituents are present on chiral carbons, the zinc coordinates with the hydroxy substituents, directing cyclopropanation to the same face, which may or may not be sterically favorable:[8]
The Simmons-Smith reagent, namely diiodomethane and diethylzinc, can react with allylic thioethers to generate sulfur ylides, which can subsequently undergo a 2,3-sigmatropic rearrangement, and will not cyclopropanate an alkene in the same molecule unless excess Simmons-Smith reagent is used:[9]
Asymmetric Simmons-Smith reaction
Although asymmetric cyclopropanation methods based on diazo compounds (see bisoxazoline ligand) exist since 1966, the asymmetric Simmons-Smith reaction was introduced in 1992 [10] with a reaction of cinnamyl alcohol with diethylzinc, diiodomethane and a chiral disulfonamide in dichloromethane:
The hydroxyl group is a prerequisite serving as an anchor for zinc. In another version of this reaction the ligand is based on salen and Lewis acid DIBAL is added:[11]
References
- ^ Howard Ensign Simmons, Jr.; Smith, R.D. (1958). "4-Substituted-2,3,5-pyrrolidinetriones". J. Am. Chem. Soc. 80: 532. doi:..
- ^ Simmons, H.E.; Smith, R.D. (1959). "A New Synthesis of Cyclopropanes". J. Am. Chem. Soc. 81: 4256. doi:.
- ^ Denis, J.M.; Girard, J.M.; Conia, J.M (1972). "Improved Simmons-Smith Reactions". Synthesis 1972: 549. doi:.
- ^ Smith, R. D.; Simmons, H. E.. "Norcarane". Org. Synth.; Coll. Vol. 5: 855.
- ^ Ito, Y.; Fujii, S.; Nakatuska, M.; Kawamoto, F.; Saegusa, T. (1988). "One-Carbon Ring Expansion Of Cycloalkanones To Conjugated Cycloalkenones: 2-Cyclohepten-1-one". Org. Synth.; Coll. Vol. 6: 327.
- ^ Simmons, H. E. et al. (1973). (Review)Org. React. 20: 1.
- ^ Girard, C.; Conia, J. M. (1978). (Review)J. Chem. Res. (S): 182.
- ^ Paul A. Grieco, Tomei Oguri, Chia-Lin J. Wang, and Eric Williams (1977). "Stereochemistry and total synthesis of (±)-ivangulin". J. Org. Chem 42: 4113. doi:.
- ^ Cohen, T.; Kosarych, Z. (1982). "Complete regio- and stereospecificity in the Lewis acid catalyzed Diels-Alder reactions of (Z)-2-methoxy-1-(phenylthio)-1,3-butadienes. Conversion of the CS configuration of an adduct to the CC configuration at the allylic position by a [2,3] sigmatropic rearrangement". J. Org. Chem 47: 4005. doi:.
- ^ Hideyo Takahashi, Masato Yoshioka, Masaji Ohno and Susumu Kobayashi (1992). "A catalytic enantioselective reaction using a C2-symmetric disulfonamide as a chiral ligand: cyclopropanation of allylic alcohols by the Et2Zn-CH2I2-disulfonamide system". Tetrahedron Letters 33 (18): 2575–2578. doi:.
- ^ Hiroaki Shitama and Tsutomu Katsuki (2008). "Asymmetric Simmons–Smith Reaction of Allylic Alcohols with Al Lewis Acid/N Lewis Base Bifunctional Al(Salalen) Catalyst". Angew. Chem. Int. Ed. 47: 2450. doi:.
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