Microwave Promoted Acetalization of Aldehydes and Ketones

(Diacetoxyiodo)benzene-Mediated C-H Oxidation of Benzylic Acetals

A useful oxidation of C-H bond of benzylic acetals has been achieved. This method avoids the use of stoichiometric metals and is compatible with the presence of both electron-donating and electron-withdrawing substituents on the aromatic ring. Oxidation was carried out by rapid microwave irradiation of benzylic acetals with PhI(OAc)₂ as the oxidant. This led to the oxidation of acetals into 2-acetoxy-1,3-dioxolanes. Furthermore, this transformation protocol encompasses a wide range of valuable conversions of these useful synthons into different carboxylic acid derivatives.

Synthesis of anthropomorphic molecules: the NanoPutians

Described here are the synthetic details en route to an array of 2-nm-tall anthropomorphic molecules in monomeric, dimeric, and polymeric form. These anthropomorphic figures are called, as a class, NanoPutians. Using tools of chemical synthesis, the ultimate in designed miniaturization can be attained while preparing the most widely recognized structures: those that resemble humans.

Microwave-assisted preparation of cyclic ketals from a cineole ketone as potential cosmetic ingredients: solvent-free synthesis, odour evaluation, in vitro cytotoxicity and antimicrobial assays

Some cyclic ketals derived from (+)1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-6-one were obtained in excellent yields by microwave activation under solvent-free conditions, as a 'green chemistry' procedure. The results obtained using acidic alumina containing 7% p-toluenesulfonic acid, as mineral support, are reported and compared with those obtained by classical methods. The new compounds were tested for their olfactive character and for a potential cosmetic use. In vitro skin cytotoxicity tests were carried out on the most promising compounds, by using NCTC 2544 human keratinocytes as target cells. They all displayed slight cytotoxic effects which were one order of magnitude lower than those found with sodium dodecylsulphate positive control. Two compounds that resulted interesting as toothpaste aromas, were submitted to antimicrobial assays and showed their activity against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus hominis, Propionibacterium acnes and Candida albicans.

Tandem Fries Reaction–Conjugate Addition under Microwave Irradiation in Dry Media; One-pot Synthesis of Flavanones

An AICl3–ZnCl2 mixture supported on silica gel is found to be an efficient medium for the Fries rearrangement of acyloxybenzene or naphthalene derivatives in solvent-free conditions under microwave irradiation.

Microwave-assisted Rapid Ketalization/Acetalization of Aromatic Aldehydes and Ketones in Aqueous Media

Aromatic aldehydes and ketones are readily acetalized or ketalized under microwave irradiation in the presence of water as a solvent.