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products from those made available by the same, non-specific mechanism acting on a given reactant. Given a single, stereoisomerically pure starting material, a stereospecific mechanism will give 100% of a particular stereoisomer (or no reaction), although loss of stereochemical integrity can easily
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mechanism, the outcome of which can show a modest selectivity for inversion, depending on the reactants and the reaction conditions to which the mechanism does not refer. The choice of mechanism adopted by a particular reactant combination depends on other factors (steric access to the reaction
109:
The quality of stereospecificity is focused on the reactants and their stereochemistry; it is concerned with the products too, but only as they provide evidence of a difference in behavior between reactants. Of stereoisomeric reactants, each behaves in its own
208:
2 mechanism. When a nucleophilic substitution results in incomplete inversion, it is because of a competition between the two mechanisms, as often occurs at secondary centres, or because of double inversion (as when iodide is the nucleophile).
73:
occur through competing mechanisms with different stereochemical outcomes. A stereoselective process will normally give multiple products even if only one mechanism is operating on an isomerically pure starting material.
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is the property of a reactant mixture where a non-stereospecific mechanism allows for the formation of multiple products, but where one (or a subset) of the products is favored by factors, such as
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is built on a combination of stereospecific transformations (for the interconversion of existing stereocenters) and stereoselective ones (for the creation of new stereocenters), where also the
88:), which could be stereospecific, or the outcome of a reactant mixture that may proceed through multiple competing mechanisms, specific and non-specific. In the latter sense, the term
314:"Overlap Control of Carbanionoid Reactions. I. Stereoselectivity in Alkaline Epoxidation," Zimmerman, H. E.; Singer, L.; Thyagarajan, B. S. J. Am. Chem. Soc., 1959, 81, 108-116.
373:
Skell, P.S. & Garner, A.Y. (1956). "The
Stereochemistry of Carbene-Olefin Reactions. Reactions of Dibromocarbene with the cis- and trans-2-Butenes".
244:
This addition remains stereospecific even if the starting alkene is not isomerically pure, as the products' stereochemistry will match the reactants'.
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The addition of singlet carbenes to alkenes is stereospecific in that the geometry of the alkene is preserved in the product. For example,
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of conjugated trienes is stereospecific in that isomeric reactants will give isomeric products. For example,
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1 mechanism whereas primary centres (except neopentyl centres) react almost exclusively by the S
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the stereochemical outcome of a given reactant, whereas a stereoselective reaction
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Ability of a chemical reaction mechanism to differentiate between stereoisomers
402:
360:
342:
Advanced
Organic Chemistry: Reactions, Mechanisms, and Structure, 3rd edition
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Eliel, E., "Stereochemistry of Carbon
Compound", McGraw-Hill, 1962 pp 434-436
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248:
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388:
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31:
50:, or which operates on only one (or a subset) of the stereoisomers.
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For example, tertiary centres react almost exclusively by the S
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itself can mean a single-mechanism transformation (such as the
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mechanism, causing only inversion, or by the non-specific
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130:
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224:-2,3-dimethyl-1,1-dibromocyclopropane, whereas the
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129:at sp centres can proceed by the stereospecific
46:reaction products from different stereoisomeric
274:reactant isomer does not react in this manner.
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156:Stereospecificity in substitution reactions
61:, that are independent of the mechanism.
376:Journal of the American Chemical Society
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262:-dimethylcyclohexadiene, whereas the
106:of a chemical compound is preserved.
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114:way. Stereospecificity towards
94:highly stereoselective reaction
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228:isomer exclusively yields the
118:is called enantiospecificity.
13:
1:
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80:is ambiguous, since the term
92:is commonly misused to mean
7:
286:
121:
64:A stereospecific mechanism
10:
425:
266:reactant isomer gives the
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150:, solvent, temperature).
146:centre in the substrate,
127:Nucleophilic substitution
258:-2,4,6-octatriene gives
42:that leads to different
293:Dynamic stereochemistry
90:stereospecific reaction
78:stereospecific reaction
252:ring closing reaction
38:is the property of a
86:Diels–Alder reaction
389:10.1021/ja01595a040
345:, New York: Wiley,
184:non-stereospecific
40:reaction mechanism
383:(14): 3409–3411.
272:trans,trans,trans
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55:stereoselectivity
36:stereospecificity
16:(Redirected from
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270:product and the
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220:-2-butene yield
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104:optical activity
100:Chiral synthesis
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409:Stereochemistry
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256:trans,cis,trans
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232:cyclopropane.
214:dibromocarbene
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44:stereoisomeric
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18:Stereospecific
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59:steric access
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53:In contrast,
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337:March, Jerry
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249:disrotatory
192:2 mechanism
182:1 mechanism
148:nucleophile
116:enantiomers
299:References
361:642506595
76:The term
66:specifies
48:reactants
32:chemistry
403:Category
339:(1985),
287:See also
122:Examples
112:specific
82:reaction
70:selects
359:
349:
268:trans
230:trans
226:trans
357:OCLC
347:ISBN
247:The
216:and
385:doi
260:cis
222:cis
218:cis
30:In
405::
381:78
379:.
355:,
319:^
307:^
96:.
34:,
391:.
387::
206:N
202:N
190:N
188:S
180:N
178:S
143:1
141:N
139:S
135:2
133:N
131:S
20:)
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