A new access to acyl- and aroyllithiums via lithium-tellurium exchange

Abstract

sugars as building blocks for replicating systems, these results direct thinking once again toward ribose itself, and chemical work seeking an improved abiotic synthesis of ribose would be most desirable.(16) Note Added in Proof: In the synthesis of these oligomers, coupling yields were ca. 90% for glycerothymine and >99% for natural nucleosides. The product oligonucleotides were purified by reversed phase HPLC (Nucleosil C-4 column, gradient from 15% to 30% acetonitrile in 0.1 M triethylammonium acetate) prior to the removal of the 5'-trityl groups and detritylated (80% acetic acid). Samples of the oligonucleotides containing the flexible base were digested with spleen phosphodiesterase, snake venom phosphodiesterase, and bacterial alkaline phosphatase. HPLC of the digests showed the expected nucleosides in their expected ratios.

One‐Pot Synthesis of Pyridyltellurium Derivatives from a Reaction with Isopropylmagnesium Chloride and X‐ray Crystal Structures of Various Pyridyl Ditellurides

“…Among the various applications of organotellurium compounds, transmetallation with organolithium or organocuprate reagents [20] is considered to be synthetically important. As a representative example, the transmetallation reaction of isopropyltelluropyridine with iPrMgCl was also carried out for CϪC bond formation.…”

α-Lithioenamines by chlorine-lithium exchange: versatile acyl anion equivalents

“…The residue obtained was dissolved in methanol with two drops of concentrated sulfuric acid and the mixture was refluxed for 1 h. The resulting mixture was treated with a saturated solution of sodium chloride and extracted with ethyl acetate. The organic layer was washed with water, dried over anhydrous Na 2 SO 4 DTBB-Catalyzed lithiation of α-chloroenamines 1 and reaction with chalcone or cyclohexyl isocyanate (Method A). Isolation of compounds 3'af, 3ah and 3bh.…”

“…2 The corresponding lithium derivatives (I) are very reactive and unstable, and have been prepared at low temperature by (a) carbonylation of some alkyllithium reagents, 3 (b) tellurium-lithium exchange, 4 and (c) in especial cases by direct deprotonation of crowded aldehydes. 5 Due to the difficulty to generate acyllithium reagents, other alternatives including mainly the use of lithiated 1,3-dithianes and related systems (II), 6 lithiated imines (III), 7,8 and other lithiated compounds 9 have been developed.…”

An approach to the synthesis of thioesters and selenoesters promoted by Rongalite®

“…Selenoesters are important intermediates in several organic transformations. Selenoesters have been used as precursors of acyl radicals 19 and anions, 20 mild acyl transfer reagents, 21 intermediates in the synthesis of ketones, 22 and for asymmetric aldol reactions. 23 Under the same conditions, we used diphenyldiselenide as source of selenolate anion, the reaction with N-acylbenzotriazoles afforded the corresponding selenoesters 5a-5d in the presence of Rongalite ® and K 2 CO 3 (Scheme 3).…”