Acetyl Bromide-Alcohols as Convenient Reaction Systems for: a) Removal ofN-tert-Boc,N-Cbz AndN-Ac Protective Groups, b) Esterifications and Transesterifications, c) Debenzylation of Aryl-O-Benzyl Ethers

1999 ◽  
Vol 29 (8) ◽  
pp. 1405-1408 ◽  
Author(s):  
Anat Lesk And ◽  
Abraham Nudelman
Keyword(s):  
Acetyl Bromide ◽  
Reaction Systems ◽  
Protective Groups ◽  
Benzyl Ethers

Visible Light-Mediated Oxidative Debenzylation

2020 ◽  
Author(s):  
Cristian Cavedon ◽  
Eric T. Sletten ◽  
Amiera Madani ◽  
Olaf Niemeyer ◽  
Peter H. Seeberger ◽  
...  
Keyword(s):  
Reaction Time ◽  
Visible Light ◽  
Functional Groups ◽  
Continuous Flow ◽  
Protecting Groups ◽  
Benzyl Ether ◽  
Complex Molecules ◽  
Protective Groups ◽  
Benzyl Ethers ◽  
Harsh Conditions

Protecting groups are key in the synthesis of complex molecules such as carbohydrates to distinguish functional groups of similar reactivity. The harsh conditions required to cleave stable benzyl ether protective groups are not compatible with many other protective and functional groups. The mild, visible light-mediated debenzylation disclosed here renders benzyl ethers orthogonal protective groups. Key to success is the use of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as stoichiometric or catalytic photooxidant such that benzyl ethers can be cleaved in the presence of azides, alkenes, and alkynes. The reaction time for this transformation can be reduced from hours to minutes in continuous flow. <br>

A Facile, Efficient and Selective Deprotection of P - Methoxy Benzyl Ethers Using Zinc (II) Trifluoromethanesulfonate

2019 ◽  
Vol 16 (12) ◽  
pp. 955-958
Author(s):  
Reddymasu Sireesha ◽  
Reddymasu Sreenivasulu ◽  
Choragudi Chandrasekhar ◽  
Mannam Subba Rao
Keyword(s):  
Room Temperature ◽  
Protecting Groups ◽  
Side Reactions ◽  
Reaction Conditions ◽  
Acid Sensitivity ◽  
Time Period ◽  
Protective Groups ◽  
Benzyl Ethers ◽  
Last Stage ◽  
Zinc Triflate

: Deprotection is significant and conducted over mild reaction conditions, in order to restrict any more side reactions with sensitive functional groups as well as racemization or epimerization of stereo center because the protective groups are often cleaved at last stage in the synthesis. P - Methoxy benzyl (PMB) ether appears unique due to its easy introduction and removal than the other benzyl ether protecting groups. A facile, efficient and highly selective cleavage of P - methoxy benzyl ethers was reported by using 20 mole% Zinc (II) Trifluoromethanesulfonate at room temperature in acetonitrile solvent over 15-120 min. time period. To study the generality of this methodology, several PMB ethers were prepared from a variety of substrates having different protecting groups and subjected to deprotection of PMB ethers using Zn(OTf)2 in acetonitrile. In this methodology, zinc triflate cleaves only PMB ethers without affecting acid sensitivity, base sensitivity and also chiral epoxide groups.

Tin(II) Bromide - Acetyl Bromide: A Mild and Efficient Reagent for Direct Conversion of Alcohol Benzyl Ethers into Acetates

Synlett ◽  
1993 ◽  
Vol 1993 (06) ◽  
pp. 437-440 ◽  
Author(s):  
Takeshi Oriyama ◽  
Mikio Kimura ◽  
Mihoko Oda ◽  
Gen Koga
Keyword(s):  
Direct Conversion ◽  
Acetyl Bromide ◽  
Benzyl Ethers ◽  
Efficient Reagent

scholarly journals Visible Light-Mediated Oxidative Debenzylation

2020 ◽  
Author(s):  
Cristian Cavedon ◽  
Eric T. Sletten ◽  
Amiera Madani ◽  
Olaf Niemeyer ◽  
Peter H. Seeberger ◽  
...  
Keyword(s):  
Reaction Time ◽  
Visible Light ◽  
Functional Groups ◽  
Continuous Flow ◽  
Protecting Groups ◽  
Benzyl Ether ◽  
Complex Molecules ◽  
Protective Groups ◽  
Benzyl Ethers ◽  
Harsh Conditions

Protecting groups are key in the synthesis of complex molecules such as carbohydrates to distinguish functional groups of similar reactivity. The harsh conditions required to cleave stable benzyl ether protective groups are not compatible with many other protective and functional groups. The mild, visible light-mediated debenzylation disclosed here renders benzyl ethers orthogonal protective groups. Key to success is the use of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as stoichiometric or catalytic photooxidant such that benzyl ethers can be cleaved in the presence of azides, alkenes, and alkynes. The reaction time for this transformation can be reduced from hours to minutes in continuous flow. <br>

EXISTENCE AND INVARIANCE FOR CONVECTION, DISPERSION, REACTION SYSTEMS WITH PRESSURE

1992 ◽  
Vol 12 (4) ◽  
pp. 443-456 ◽  
Author(s):  
Chunhong Xie ◽  
Taiping He ◽  
Guohong Bai
Keyword(s):  
Reaction Systems
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