Oxidative deprotection of tetrahydropyranyl and trimethylsilyl ethers in water using 1,4-dichloro-1,4-diazoniabicyclo[2,2,2]octane bis-chloride under neutral conditions

A facile oxidative deprotection of trimethylsilyl and tetrahydropyranyl ethers in water using 1,4-dichloro-1,4-diazoniabicyclo[2,2,2]octane bis-chloride as a new efficient reagent under neutral conditions is described. This methodology is ecofriendly and environmentally benign since it uses water as a solvent. In all reactions DABCO was regenerated, rechlorinated and reused several times.

Download Full-text

H3PW12O40 — A selective, environmentally benign, and reusable catalyst for the preparation of methoxymethyl and ethoxymethyl ethers and their deprotections under mild conditions

Canadian Journal of Chemistry ◽

10.1139/v08-068 ◽

2008 ◽

Vol 86 (8) ◽

pp. 831-840 ◽

Cited By ~ 13

Author(s):

Iraj Mohammadpoor-Baltork ◽

Majid Moghadam ◽

Shahram Tangestaninejad ◽

Valiollah Mirkhani ◽

Arsalan Mirjafari

Keyword(s):

Reaction Times ◽

Environmentally Benign ◽

Reusable Catalyst ◽

Secondary Alcohols ◽

Selective Protection ◽

Trimethylsilyl Ethers ◽

Solvent Free Conditions ◽

Benzyl Ethers ◽

High Yields ◽

Work Up

Different types of primary and secondary alcohols were efficiently transformed to their corresponding methoxymethyl (MOM) and ethoxymethyl (EOM) ethers in the presence of catalytic amounts of H3PW12O40 at room temperature under solvent-free conditions. Selective protection of primary and secondary alcohols in the presence of phenols and tertiary alcohols was achieved by this method. Deprotection of these ethers to their parent alcohols was also performed using this catalyst in ethanol under reflux conditions. We have also found that primary and secondary MOM- and EOM-ethers are selectively deprotected in the presence of phenolic and tertiary ones, methyl and benzyl ethers, esters, and trimethylsilyl ethers by this catalyst. The notable advantages of this protocol are high yields, short reaction times, easy work-up, non-toxicity, easy availability and handling, eco-friendly, and reusability of the catalyst.Key words: methoxymethylation, ethoxymethylation, protection, deprotection, heteropoly acid.

Download Full-text

Tributylhexadecylphosphonium bromide: an efficient reagent system for the one-pot synthesis of 2,4,5-trisubstituted imidazoles

Heterocyclic Communications ◽

10.1515/hc-2014-0182 ◽

2015 ◽

Vol 21 (2) ◽

Cited By ~ 1

Author(s):

Mohammad Heidari ◽

Mohsen Rezaei ◽

Rashid Badri

Keyword(s):

Cost Effectiveness ◽

Aromatic Aldehyde ◽

Ammonium Acetate ◽

Reaction Times ◽

Environmentally Benign ◽

Reaction Conditions ◽

One Pot ◽

One Pot Synthesis ◽

The One ◽

Efficient Reagent

AbstractThe reaction of benzil, an aromatic aldehyde, and ammonium acetate in ethanol at reflux in the presence of tributylhexadecylphosphonium bromide as catalyst affords a 2,4,5-trisubstituted imidazole. The present methodology offers several advantages over the literature methods, including excellent yields, shorter reaction times, environmentally benign milder reaction conditions, cost-effectiveness of catalyst, easy workup, and purification of products by nonchromatographic methods.

Download Full-text