南开大学 高等有机合成-陈悦Week 7 Monday

1,2-Dimethylcyclohexene HCl addition: At −78 degree in dichloromethane, 88% of the product is syn; At 0 degree in ether, 95% of the product results from anti addition
Although chlorination of aliphatic alkenes usually gives anti addition, syn addition is often dominant for phenyl-substituted alkenes
4.1.4. Addition of Halogens to Alkenes
Chapter 3. Functional Group Interconversion by Substitution, Including Protection and Deprotection
Nov. 10th, 2008
Benzyl ethers: Bz, PMB, DMB Cleaved by catalytic hydrogenolysis, or by electron-transfer reduction using Na/NH3 or by Lewis acids such as FeCl3 and SnCl4 or by dichlorodicyanoquinone (DDQ).
Can be removed readily by base-catalyzed hydrolysis. Trichloroethyl carbonate esters can be reductively removed with Zn. Ally carbonate can be removed by Pd catalyzed reaction.
3.5.3. Carbonyl-Protecting Groups Acetals
3.5.3. Carbonyl-Protecting Groups 1,3-oxathiolane derivative
Dithioketals, cyclic dithiolanes Can be formed from the corresponding dithiols or Di-n-butylstannyldithiolates by Lewis acid–catalyzed reactions:
3.5.1.4. Esters as Protective Groups Acetates, benzoates, and pivalates, can be conveniently prepared by reaction of unhindered alcohols with acetic anhydride, benzoyl chloride, or pivaloyl chloride, respectively. Pyridine or 4-Dimethylaminopyridine (DMAP) is often used as a catalyst.
Alkenes that can give rise to a particularly stable carbocation are likely to react via the ion pair mechanism, It might be expected that the ion pair mechanism would lead to a preference for syn addition,
Chapter 4. Electrophilic Additions to Carbon-Carbon Multiple Bonds
Nov. 10th, 2008
Introduction
4.1. Electrophilic Addition to Alkenes 4.1.1. Addition of Hydrogen Halides
4.1.6. Addition Reactions with Electrophilic Sulfur and Selenium Reagents
4.1.6. Addition Reactions with Electrophilic Sulfur and Selenium Reagents anti-Markovnikov orientation
Cleaved by HNO3, t-BuOCl,NaClO2, PhIO2C(CF3)2, DDQ, SbCl5, and cupric salts
3.5.4. Carboxylic Acid–Protecting Groups Oxazoline derivative
Orthoesters, 4-methyl-2,6,7-trioxabicyclo[2.2.2]octane, can be hydrolyzed easily
Markovnikov orientation
4.1.6. Addition Reactions with Electrophilic Sulfur and Selenium Reagents anti-Markovnikov orientation
Markovnikov orientation
Markovnikov orientation
4.1.6. Addition Reactions with Electrophilic Sulfur and Selenium Reagents anti-Markovnikov orientation
Markovnikov orientation
4.1.6. Addition Reactions with Electrophilic Sulfur and Selenium Reagents anti-Markovnikov orientation
4.1.2. Hydration and Other Acid-Catalyzed Additions of Oxygen Nucleophiles
4.1.3. Oxymercuration-Reduction
4.1.3. Oxymercuration-Reduction
4.1.3. Oxymercuration-Reduction
1.
2.
3.
4.1.4. Addition of Halogens to Alkenes
4.1.4. Addition of Halogens to Alkenes
4.1.5. Addition of Other Electrophilic Reagents
4.1.6. Addition Reactions with Electrophilic Sulfur and Selenium Reagents
3.5.2. Amino-Protecting Groups Phthalimides
Trifluoroacetyl
3.5.2. Amino-Protecting Groups 4-pentenoyl group
cyclic bis-silyl derivatives
Readily removed by hydrolysis
3.5.1.3. Silyl Ethers as Protective Groups TMS, TES, TBDMS, TBDPS, TPS, TIPS, TBODPS Introduced by halide or triflate Removed by hydrolytic conditions (acidic), or TBAF, methanolic NH4F, or aqueous HF, BF3, or SiF4 Hydrolytic stability of the various silyl protecting groups is in the order: TMS < TES < TBDMS < TIPS < TBDPS (Steric effect) TBODPS are more sensitive tቤተ መጻሕፍቲ ባይዱ fluoride than TBDMS and TBDPS
3.5.1.5. Protective Groups for Diols Introduction:
Removal: Can be readily removed by aqueous acid
3.5.2. Amino-Protecting Groups
Cbz
BOC
Ally Carbamate
Hg
O
OAc Hg Hg AcO OH H H R R H H2O H O R OH
H H2O
H
4.1.3. Oxymercuration-Reduction
RE
Rz TBDPSO
Me
4.1.3. Oxymercuration-Reduction
4.1.4. Addition of Halogens to Alkenes