Development of dynamic kinetic resolution on large scale for (±)-1-phenylethylamine

• Lisa K. Thalén and
• Jan-E. Bäckvall

Beilstein J. Org. Chem. 2010, 6, 823–829, doi:10.3762/bjoc.6.97

• product mixture. However, by racemizing the slower reacting enantiomer in situ, in a process known as dynamic kinetic resolution (DKR) [11], a theoretical yield of 100% can be achieved. We have previously developed a highly efficient protocol for the DKR of primary amines using Candida antarctica lipase B

• uncatalyzed chemical acylation of the substrate occurs at elevated temperatures when using acyl donors of this type in the DKR of primary amines. This has been overcome by initially adding one equivalent of the acyl donor followed by a later addition of 0.1 equiv of the acyl donor to allow the reaction to go

Molecular recognition of organic ammonium ions in solution using synthetic receptors

• Andreas Späth and
• Burkhard König

Beilstein J. Org. Chem. 2010, 6, No. 32, doi:10.3762/bjoc.6.32

Synthesis of 3-(phenylazo)-1,2,4-triazoles by a nucleophilic reaction of primary amines with 5-chloro- 2,3-diphenyltetrazolium salt via mesoionic 2,3-diphenyltetrazolium- 5-aminides

• Shuki Araki,
• Satoshi Hirose,
• Yoshikazu Konishi,
• Masatoshi Nogura and
• Tsunehisa Hirashita

Beilstein J. Org. Chem. 2009, 5, No. 8, doi:10.3762/bjoc.5.8

• amines have been examined. In the presence of an inorganic base such as NaHCO3, primary and secondary amines undergo a nucleophilic substitution to give the corresponding 5-aminotetrazolium salts. When triethylamine is used as a base, primary amines give 3-phenylazo-1,2,4-triazoles. A plausible dual-path

• hydrogencarbonate, 4a was obtained exclusively (Scheme 1). The results with other amines are summarized in Table 1. The reaction of butylamine showed a similar tendency: with the triethylamine base triazole 3b was obtained, whereas with sodium hydrogencarbonate 5-aminotetrazolium 4b was formed. Other primary amines

• , such as ethanolamine and ethyl glycinate gave the corresponding triazoles 3c and 3d. Interestingly, sterically bulky primary amines as well as secondary amines gave the respective 5-aminotetrazolium salts 4d–h. It is worthy to note that the reaction of isopropylamine/triethylamine gave 3

One-pot preparation of substituted pyrroles from α-diazocarbonyl compounds

• Fernando de C. da Silva,
• Mauricio G. Fonseca,
• Renata de S. Rianelli,
• Anna C. Cunha,
• Maria C. B. V. de Souza and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2008, 4, No. 45, doi:10.3762/bjoc.4.45

• -carbaldehyde (6) followed by reaction with primary amines. Keywords: diazocarbonyl; dihydrofuran; one-pot synthesis; pyrrole; Introduction The pyrrole unit [1] occurs in many interesting classes of compounds such as pharmaceutical agents [2][3][4][5], conducting polymers [6][7], molecular optics [8][9][10

• hexane-2,5-dione and primary amines under microwave irradiation. Other processes including several clay-mediated synthetic variations of these classical methods also have been reported for preparing pyrroles in equal or better yields [21]. In 2001 [22] and 2004 [23], Banik and co-workers, by using the

• variations in the reaction times (see Table 1). The reaction of the dihydrofuran intermediates 4, 5 and 6 with excess of primary amines in the presence of glacial acetic acid afforded the corresponding substituted pyrroles 7a–n in moderate to good yields (Table 1). Slightly different reactivity between 4, 5

The role of an aromatic group in remote chiral induction during conjugate addition of α-sulfonylallylic carbanions to ethyl crotonate

• Shlomo Levinger,
• Ranjeet Nair and
• Alfred Hassner

Beilstein J. Org. Chem. 2008, 4, No. 32, doi:10.3762/bjoc.4.32

• series of α-sulfonylallylic donor precursors 1, bearing a remote stereogenic center, were prepared by condensing a chiral aryl- or heteroarylalkylamine 6 with the bromo-substituted allyl sulfone 5 [2] (Scheme 2 and Table 1). Of the primary amines 6 used for generation of amino-substituted sulfones 1, 1

• -carbonitrile was indicated by formation of a 10-tert-butyl derivative on reaction with tert-butylmagnesium chloride [9]. However, since iminium ion intermediates are much more reactive than ketones [7], imines 8h and 8j were successfully reduced to the primary amines 6 upon treatment with sodium

Variations in product in reactions of naphthoquinone with primary amines

• Marjit W. Singh,
• Anirban Karmakar,
• Nilotpal Barooah and
• Jubaraj B. Baruah

Beilstein J. Org. Chem. 2007, 3, No. 10, doi:10.1186/1860-5397-3-10

• Marjit W. Singh Anirban Karmakar Nilotpal Barooah Jubaraj B. Baruah Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039 Assam, India 10.1186/1860-5397-3-10 Abstract Reaction of 1,2-naphthoquinone with primary amines gives a 2-amino-1,4-naphthoquinone derivative

• -benzoquinone reacts with primary amines to give 2,5-diamino 1,4-benzoquinones; similar reaction of 1,4-naphthoquinone with primary amines results in the formation of 2-amino 1,4-naphthoquinones. [13] However, the product formed from such simple reaction of amine with various quinones has much scope for

• exploration, especially in terms of synthesis of electro/photoactive supramolecular assemblies or polymers. In this communication we describe preliminary account of results obtained on the equivalence of reaction of 1,2-naphthoquinone and 1,4-naphthoquinone with primary amines. Results and discussion It is

Synthesis and glycosidase inhibitory activity of new hexa- substituted C8-glycomimetics

• Olivia Andriuzzi,
• Christine Gravier-Pelletier,
• Gildas Bertho,
• Thierry Prangé and
• Yves Le Merrer

Beilstein J. Org. Chem. 2005, 1, No. 12, doi:10.1186/1860-5397-1-12

• side of the bulky TBDMS group in β-position. However, it has to be pointed out that more hindered nucleophiles, such as primary amines, revealed unable to open the cyclic sulfate 9 or 10. The absolute configurations of 11 and 12 were established by NMR studies. 1H signals were assigned (Table 1) using