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Amines can be synthesized by treating an _____ with ____ and leads to a _____
- Alkyl halide
- Ammonia or another amine
- Mixture of products
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Reductive amination
First form an imine, followed by NaBH4 reduction
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What can be used to accomplish reductive amination in a single step?
NaBH3CN
It has a smaller partial negative charge than NaBH4. It is also less basic and remains in tact in slightly acidic conditions
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Umpolung
Reversing charge at a particular atom
Ex. when a wittig reagent is formed
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Grignard and alkyl lithium reagents are added via ____ addition, while Gilman reagents are added in ____ addition
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In C-C bond forming reactions:
Direct 1,2 bond (relative positioning: 1,2)
opening of an epoxide or direct addition with a hard nucleophile
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In C-C bond forming reactions:
Conjugate 1,2 bond (relative positioning: 1,4)
Conjugate addition with a soft nucleophile
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In C-C bond forming reactions:
2,3 enolate (relative positioning: 1,3)
Aldol reaction or alkylation of the alpha carbon
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In C-C bond forming reactions:
2,3 enolate (relative positioning: 1,5)
Conjugate addition with enolate
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Clemmensen reaction
- Creates new CH2 bond from C=O
- Ketone or aldehyde is refluxed in Zn/Hg and HCl solution
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In the Clemmensen Reduction, the zinc metal participates in a dissolving metal reduction where _____
the metal solubilizes in the solution when it comes into contact with the ketone or aldehyde, and the reaction ensues
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Raney-Nickel Reduction
Reduces carbonyl carbon to a methylene group
- Ketone or aldehyde is converted to thioacetal
- Thioacetal becomes methylene
- Thiol, in acid and water
- Raney Nickel reagent, H2
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When should the Wolf-Kishner reaction be avoided?
If there is a functional group that is susceptible to reaction under basic conditions or with a strong nucleophile
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When should the Clemmensen reaction be avoided?
If there is a functional group that is susceptible to reaction under acidic conditions
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When should Raney-Nickel be avoided?
If there is a functional group that is susceptible to reaction with nucleophilic thiols (RSH) or with H2 in the presence of a metal catalyst
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Selective reagent
A reagent that will help us select one type of reaction or one location on the molecule over others
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