Term
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Definition
| compound that contains C-metal bond |
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Term
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Definition
-organomagnesium compound
-prepared by addition of alkyl, aryl or alkenyl (vinylic) halide to Mg metal in diethyl ether (THF) |
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Term
| Grignard reagent preparation |
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Definition
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Term
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Definition
| prepared by reaction of alkyl, aryl, or alkenyl (vinylic) halide w/ lithium metal |
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Term
| Preparation of organolithium reagents |
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Definition
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Term
| C-metal bonds in RMgX and RLi: |
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Definition
best described as polar covalent
-chart in slides (15-6) |
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Term
| RMgX and RLi are valuable in synthesis as what? |
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Definition
-nucleophiles
-C bearing halogen is transformed from electrophile to nucleophile
-most valuable use is addition to electrophilic C of C=O group of aldehydes, ketones, carboxylic esters, and acid chlorides to form new C-C bonds
-Ex. in slides (15-7) |
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Term
| Reaction of RMgX and RLi w/ proton acids |
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Definition
-RMgX and RLi=strong bases
-They remove the following acidic protons readily:
*R2NH
*RC-=CH (triple bond)
*ROH
*HOH
*ArOH
*RSH
*RCOOH
-Ex. slides (15-8)
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Term
| Reaction of RMgX and RLi w/ oxiranes (epoxides) |
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Definition
-Reaction of RMgX or RLi w/ oxirane followed by protonation gives primary alcohol w/ a C chain 2 C's longer than original chain
-Ex. slides (15-9) |
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Term
| RMgX and RLi reaction w/ oxiranes (epoxides) |
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Definition
-Major product corresponds to SN2 attack of RMgX or RLi on less hindered C of the epoxide
-Ex. slides (15-10) |
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Term
| Gilman reagents (preparation) |
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Definition
-Lithium diorganocopper reagents
-prepared by treating alkyl, aryl, or alkenyl lithium compound w/ Cu(I) iodide
-Ex. slides (15-11) |
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Term
Gilman reagents:
coupling w/in organohalogen compounds does what? |
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Definition
-Forms a new C-C bond by coupling w/ alkyl and alkenyl chlorides, bromids, and iodides
-Ex. slides (15-12) |
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Term
Gilman reagents:
coupling w/ vinylic halides... |
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Definition
-stereospecific
*configuration of C=C is retained
-Ex. slides (15-13) |
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Term
| Variation on Gilman reagent preparation |
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Definition
-Use a Grignard reagent w/ catalytic amount of Cu(I) salt
-Ex. slides (15-14) |
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Term
| Gilman reagent reaction w/ epoxides |
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Definition
-Ring opening is regioselective
-Ex. slides (15-15) |
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Term
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Definition
-Carbene, R2C: neutral molecule where a C atom is surrounded by only 6 valence electrons
-Methylene=simplest carbene
*Prepared by photolysis/thermolysis of diazomethane
*Ex. in slides (15-16)
*Methylene prepared this way is so nonselective it's of little synthetic use |
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Term
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Definition
-in its lowest electronic state, carbon is sp2 hybridized w/ unshared pair of electrons occupying the 3rd sp2 orbital
-Ex. slides (15-17) |
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Term
| Dichlorocarbene preparation |
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Definition
-Treat chloroform w/ potassium tert-butoxide
-Ex. slides (15-18) |
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Term
| Dichlorocarbene :CCl2 reacts w/ alkenes to form what? |
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Definition
-Forms dichlorocyclopropanes
-Exs. slides (15-19) |
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Term
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Definition
-a way to add methylene to alkene to form cyclopropane
-Generation of Simmons-Smith reagent in slides (15-20)
-This organozinc reacts w/ wide variety of alkenes to give cyclopropanes
-Exs. slides (15-21) |
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Term
| Simmons-Smith reaction mechanism |
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Definition
-organozinc compound reacts w/ an alkene by a concerted mechanism
-Ex. slides (15-22) |
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