a) L. Grehn and U. Ragnarsson, Angew. Chem., 1985, 97, 519–520 ( Angew. Chem., Int. Ed. Engl., 1985, 24, 510–511) CrossRef CAS; J. Symersky, P. Malon, L. Grehn and U. Ragnarsson, Acta Crystallogr., Sect. C: Cryst. Struct. Commun., 1990, 46, 683–686 CrossRef. Paclitaxel is a drug of immense medicinal and commercial interest, originally isolated from the bark of the Pacific yew tree. It inhibits cell division and is therefore used in the treatment of various types of cancer. Structurally it is composed of a highly functionalized tetracyclic skeleton with one carbonyl and two free hydroxyls and another four esterified such, one of which in the A-ring notably in this context with a N-benzoylated β-amino acid sidechain. Several elegant total syntheses of the drug have been reported. A related drug of comparable importance is docetaxel in which one of the previously mentioned paclitaxel skeleton ester groups in the B-ring is replaced by a free hydroxyl and the sidechain N-benzoyl group is missing and instead substituted with a Boc-group. a) R. D. Connell, T. Rein, B. Åkermark and P. Helquist, J. Org. Chem., 1988, 53, 3845–3849 CrossRef CAS; There is nothing better than being able to follow the teacher when exercising at the gym and that is why Pratique em Casa has live with our teachers, where you will have the right accompaniment for your exercises.

a) K. Juhl, N. Gathergood and K. A. Jørgensen, Angew. Chem., 2001, 113, 3083–3085 ( Angew. Chem., Int. Ed. Engl., 2001, 40, 2995–2997) CrossRef; However, since the 1970s, it has been understood that the granting of free pratique could be considered a ‘formality’ such that a Master could tender the NOR with free pratique having been formally granted by the port in circumstances where there was no reason to fear delay on crew health grounds.C. Hulme, J. Peng, G. Morton, J. M. Salvino, T. Herpin and R. Labaudiniere, Tetrahedron Lett., 1998, 39, 7227–7230 CrossRef CAS. Synthesis and properties of N-Boc-acylamides [RCONR 1(Boc)] 12 Formamides, acetamides and benzamides are quite stable compounds, and often require heating in strongly acidic or basic solution for their cleavage. 4 Unless severely sterically hindered they generally react with a slight excess of Boc 2O and catalytic amounts of DMAP under carbon dioxide evolution to the corresponding Boc-acylamides (acylcarbamates) within 1–20 h at room temperature in essentially quantitative yields. 13 Their aminolysis was occasionally slow, whereas hydrazinolysis was much faster. In this way N-formyl, -acetyl and -benzoyl protecting groups could be cleaved under much milder conditions than before. 14 Both steps could also be combined in a one-pot reaction procedure. Discrimination between amino functions of mixed primary/ secondary amines via acylation and subsequent treatment with Boc 2O/ DMAP is feasible, because after the acylation step obviously only the primary groups can react. This was demonstrated by selective cleavage of N-acetyl from the primary amino groups of spermidine. 15 A Reaxys search (June 2013) for R-N(Boc) 2, R any group except hydrogen, gave 5630 hits and for R-NCbz(Boc) 230 hits. G. Höfle, W. Steglich and H. Vorbrüggen, Angew. Chem., 1978, 90, 602–615 ( Angew. Chem., Int. Ed. Engl., 1978, 17, 569–583) CrossRef and references therein. M. M. Hansen, A. R. Harkness, D. S. Coffey, F. G. Bordwell and Y. Zhao, Tetrahedron Lett., 1995, 36, 8949–8952 CrossRef CAS.

La perspective practique publiée en 1651 est la deuxième édition du traité de perspective et réunit les trois volumes publiés en 1642, 1647 et 1649. The articles of the SO Series have a practicle pressure lid, realized in polyethylene, with tamper evident seal to the first use.Boc 2N-compounds were originally prepared from urethanes with Boc 2O/ DMAP. 13 For amine synthesis from halides alkylation of Boc 2NH is rather convenient. Similarly, alkylation of Cbz(Boc)NH provided a product of type Cbz(Boc)N-R. 34 Reacting an easily obtained Cbz-protected spermidine substrate with Boc 2O/ DMAP ultimately provided N 8-Boc- N 1-Cbz-spermidine via a derivate of this kind, i.e. full discrimination between two primary and one secondary amino functions was accomplished. 35a In the same way Cbz-hydrazine served as a reagent for stepwise alkylation/ acylation of hydrazine. 35b,c Also chiral products of these and related types have been obtained in the presence of a proper ligand. 36 The reactions of Boc 2O with amines and alcohols in the presence and absence of DMAP have been investigated by Basel and Hassner with respect to products and mechanisms under widely varying conditions. 45 Different products were obtained depending on the ratio of reagents, polarity of the solvent and type of amine used. Without DMAP aliphatic amines gave Boc-derivatives in quantitative yields. In the presence of DMAP isocyanate formation was favoured at low temperatures, whereas otherwise in addition to Boc- and Boc 2-amine also urea and carbamic-carbonic anhydrides and related substances could be isolated. It was suggested that carbamic acids could occasionally play a role as reaction intermediates. Aliphatic alcohols gave O-Boc derivatives and symmetrical carbonates in the presence of DMAP. From cysteine methyl ester in the presence of DMAP, the N-Boc-, N, S-Boc 2- and N, N, S-Boc 3-derivatives could all be isolated. b) U. Ragnarsson, L. Grehn, L. S. Monteiro and H. L. S. Maia, Synlett, 2003, 2386–2388 CrossRef CAS. f) J. Zheng, B. Yin, W. Huang, X. Li, H. Yao, Z. Liu, J. Zhang and S. Jiang, Tetrahedron Lett., 2009, 50, 5094–5097 CrossRef CAS.