Zn in ionic liquid: an efficient reaction media for the synthesis of diorganyl chalcogenides and chalcogenoesters

Synthesis of 1,3,4-oxadiazole derivatives from α-amino acid and acyl hydrazides under thermal heating or microwave irradiation conditions

“…As part of our growing interest in using α-amino acids as chiral building blocks in organic synthesis, [36][37][38] and in connection with the increasing importance of the synthesis of small libraries of compounds with programmed variations of substituents, we describe herein an easy and inexpensive one-pot synthetic route for the preparation of a set of chiral N-protected chiral α-amino acid derived 1,3,4-oxadiazoles under conventional thermal heating and microwave irradiation, as depicted in the Scheme 1. The synthetic route to afford the 1,3,4-oxadiazoles was applied on appropriately protected amino acids shown in Figure 1.…”

Atom Efficient Preparation of Zinc Selenates for the Synthesis of Selenol Esters under “On Water” Conditions

“…As a consequence of the increasing demand for selenol esters, the number of methods to prepare this class of compounds has been increased along the years [1,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43] Among the strategies to prepare selenol esters there are the reactions of nucleophilic selenium reagents with an acyl group source, such as N -acyl benzotriazoles [17,18] activated carboxylic acids (using DCC [3] or PBu 3 [4,5,19,20]), enol esters [21], anhydrides [22,23,24], esters [25], carbon monoxide [26,27], aldehydes [28,29] or acyl chlorides [2,7,30,31,32,33,34,35,36,37,38,39,40,41,42,43]. Other approaches to selenol esters involve the alkylation of selenocarboxylate anions with alkyl h...…”

“…The acyl substitution of acyl chlorides is by far the most explored method to access selenol esters, mainly because of its versatility, since the diversity of acyl chlorides that can be prepared is practically endless. The pivotal step in this reaction is the generation of the nucleophilic selenium species and a range of reagents have been used for this purpose, including Se°/ArMgBr [2], (NH 2 ) 2 C=Se/Et 3 N [30], Se°/NaBH 4 [6], InI/(PhSe) 2 [31,39,40], Se°/LiAlH 4 [32,37], (RSe) 2 /Zn/AlCl 3 [33], Ph(NH 2 )C=Se [34], (Bu 3 Sn) 2 /(PhSe) 2 /hv [35,36], Se°/R 2 C=CZrCp 2 Cl [38], (RSe) 2 /Zn°/[bmim]PF 6 [41], (PhSe) 2 /Hg°/dioxane [42] and (PhSe) 2 /SnCl 2 /CuBr 2 /[bmim]BF 4 [43]. Despite these reaction systems afforded a range of selenol esters, they suffer from one or more of the following drawbacks: use of VOCs as solvent, strong bases, strong and moisture sensible reducing agents, expensive reagents and low atom-economy.…”

Improved synthetic routes to the selenocysteine derivatives useful for Boc-based peptide synthesis with benzylic protection on the selenium atom

“…[20][21][22] Later, more reactive bromoalanines were utilized for the synthesis of Sec derivatives. 15,[23][24][25][26] 12 the amino group of L-serine (3) was protected with Boc, and the obtained carbamate 4 was converted into methyl ester 5 (Scheme 1). The Ser derivative thus protected was tosylated to 6 and then selenated to 7 by reaction with a selenolate, which was generated from di(p-methylbenzyl) diselenide (MBnSeSeMBn) and NaBH 4 in MeOH, according to a similar procedure reported by Braga.…”