Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time, and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space. While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes, vast areas of the tropics remain understudied. In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity, but it remains among the least known forests in America and is often underrepresented in biodiversity databases. To worsen this situation, human-induced modifications may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge, it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Curiosities About The Aldol Reaction Employed As A Key Step In The Synthesis Of Pteridic Acids A And B [curiosidades Sobre A Reação Aldólica Utilizada Como Etapa Chave Na Síntese Brasileira Dos ácidos Pterídicos A E B]

This work describes an overview of our synthesis of pteridic acids A and B and discloses some interesting results related to the lithium enolate-mediated aldol reaction used as key step to set up the C5-C15 fragment of these natural products. This first example, as far we know, of an aldol reaction between a chiral enolate of a (Z) enone and a chiral aldehyde has driven us to a series of experiments showing the remarkable relation between enolization selectivity and reaction conditions.331020322037Ygarashi, Y., Yoshida, R., Furumai, T., (2002) J. Antibiot., 55, p. 764. , A numeração para os carbonos dos ácidos pterídicos segue a mesma adotada nesta referênciaEvans, I.A., Mason, J., (1965) Nature, 208, p. 913Centro de Informação Toxicológica Do Rio Grande Do sul, , http://www.cit.rs.gov.br, acessada em Março 2010Dias, L.C., Salles Jr., A.G., (2009) J. Org. Chem., 74, p. 5584Rocha, D.R., (2009) Rev. Virtual Quim., 1, p. 182Nakahata, T., Fujimura, S., Kuwahara, S., (2006) Chem. Eur. 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The First Examples Of The Enantioselective Heck-matsuda Reaction: Arylation Of Unactivated Cyclic Olefins Using Chiral Bisoxazolines

Successful enantioselective Heck-Matsuda arylations were accomplished for the first time using chiral bisoxazolines as ligands. Enantioselective Heck arylations were performed with several cyclic nonactivated olefins to provide the Heck products in 63-96% isolated yields and in enantiomeric excesses of 54% up to 84%. © 2012 Elsevier Ltd. All rights reserved.532633253328Tietze, L.F., Ila, H., Bell, H.P., (2004) Chem. Rev., 104, p. 3453Melchiorre, P., Marigo, M., Carlone, A., Bartoli, G., (2008) Angew. Chem., Int. Ed., 47, p. 4137Walsh, P.J., Kozlowski, M., (2009) Fundamentals of Asymmetric Catalysis, , University Science Books Sausalito pp. 549-576Roglans, A., Pla-Quintana, A., Moreno-Manas, M., (2006) Chem. Rev., 106, p. 4622. , For reviews, seeTaylor, J.G., Moro, A.V., Correia, C.R.D., (2011) Eur. J. Org. Chem., p. 1403Felpin, F.-X., Nassar-Hardy, L., Callonnec, F.L., Fouquet, E., (2011) Tetrahedron, 67, p. 2815Nassar-Hardy, L., Fabre, S., Amer, A.M., Fouquet, E., Felpin, F.-X., (2012) Tetrahedron Lett., 53, p. 338Schwalm, C.S., De Castro, I.B.D., Ferrari, J., De Oliveira, F.L., Aparicio, R., Correia, C.R.D., (2012) Tetrahedron Lett., 53, p. 1660Taylor, J.G., Correia, C.R.D., (2011) J. Org. Chem., 76, p. 857Da Penha, E.T., Forni, J.A., Biajoli, A.F.P., Correia, C.R.D., (2011) Tetrahedron Lett., 52, p. 6342Taylor, J.G., Ribeiro, R.S., Correia, C.R.D., (2011) Tetrahedron Lett., 52, p. 3861De Azambuja, F., Correia, C.R.D., (2011) Tetrahedron Lett., 52, p. 42Siqueira, F.A., Taylor, J.G., Correia, C.R.D., (2010) Tetrahedron Lett., 51, p. 2102Garcia, A.L.L., Carpes, M.J.S., Montes De Oca, A.C.B., Santos, M.A.G., Santana, C.C., Correia, C.R.D., (2005) J. Org. Chem., 70, p. 1050Garcia, A.L.L., Correia, C.R.D., (2003) Tetrahedron Lett., 44, p. 1553Severino, E.A., Costenaro, E.R., Garcia, A.L.L., Correia, C.R.D., (2003) Org. Lett., 5, p. 305Kikukawa, K., Matsuda, T., (1977) Chem. Lett., p. 159Johnson, J.S., Evans, D.A., (2000) Acc. Chem. Res., 33, p. 325Evans, D.A., Scheidt, K.A., Johnston, J.N., Willis, M.C., (2001) J. Am. Chem. Soc., 123, p. 4480Evans, D.A., Johnston, J.N., (1999) Org. Lett., 1, p. 865Evans, D.A., Johnson, D.S., (1999) Org. Lett., 1, p. 5985Nishiyama, H., Sakaguchi, H., Nakamura, T., Horihata, M., Kondo, M., Itoh, K., (1989) Organometallics, 8, p. 846. , For PyBox ligand seeTietze, L.F., Sommer, K.M., Zinngrebe, J., Stecker, F., (2005) Angew. Chem., 117, p. 262. , For an excellent example of a conventional Heck reaction employing chiral bisoxazoline as ligand, see:, Angew. Chem. Int. Ed. 2005, 44, 257Pastre, J.C., Correia, C.R.D., (2009) Adv. Synth. Catal., 351, p. 1217Pastre, J.C., Genisson, Y., Saffon, N., Dandurand, J., Correia, C.R.D., (2010) J. Braz. Chem. Soc., 21, p. 821. , For previous attempts of an enantioselective HM reaction using chiral ionic liquids, seeAshimori, A., Overman, L.E., (1992) J. Org. Chem., 57, p. 4571Amatore, C., Jutand, A., Suarez, A., (1993) J. Am. Chem. Soc., 115, p. 9531Cabri, W., Candiani, I., Bedeschi, A., Santi, R., (1993) J. Org. Chem., 58, p. 7421Sato, Y., Sodeoka, M., Shibasaki, M., (1990) Chem. Lett., 1953Sato, Y., Watanabe, S., Shibasaki, M., (1992) Tetrahedron Lett., 33, p. 2589Sato, Y., Nukui, S., Sodeoka, M., Shibasaki, M., (1994) Tetrahedron, 50, p. 371Shibasaki, M., Sodeoka, M., (1994) J. Synth. Org. Chem. Jpn., 52, p. 955Grunewald, G.L., Ye, Q., (1988) J. Org. Chem., 53, p. 4021. , For application of similar carbocycles in the synthesis of bioactive molecules seeMoriaty, R.M., Enache, L.A., Zhao, L., Gilardi, R., Mattson, M.V., Prakash, O., (1998) J. Med. Chem., 41, p. 468Hancock, R.D., (1992) J. Chem. Edu., 69, p. 615. , For an interesting reviewMoro, A.V., Cardoso, F.S.P., Correia, C.R.D., (2009) Org. Lett., 11, p. 3642Prediger, P., Barbosa, L.F., Genisson, Y., Correia, C.R.D., (2011) J. Org. Chem., 76, p. 773

Concerning The Application Of The1h Nmr Abx Analysis For Assignment Of Stereochemistry To Aldols Deriving From Aldehydes Lacking β-branches

Attempts to apply the 1H NMR ABX method for assignment of stereochemistry of β-hydroxy ketones to aldols 4-10 deriving from α-methyl aldehydes lacking β-branches reveals that the presence of a β-branch in the aldehyde reaction partner is necessary so that the average chemical environment of Ha and Hb is different for the Felkin and anti-Felkin aldols (see conformational pairs A/B and C/D, respectively). When the chiral α-methyl aldehyde lacks a β-branch, as in the case of the aldehyde precursors to 4-10, the conformational energies of E and F (for the Felkin β-hydroxy ketone derivatives), and conformers G and H for the anti-Felkin aldols, are too close in energy (within each pair), such that the average chemical and magnetic environments of Ha and Hb in the two diastereomers cannot be easily distinguished. This analysis provides a rational basis for application of the 1H NMR ABX pattern analysis to other β-hydroxy ketone derivatives. © 2005 American Chemical Society.70251046110465Dias, L.C., Baú, R.Z., De Sousa, M.A., Zuckerman-Schpector, J., (2002) Org. Lett., 4, p. 4325Liu, C.M., Smith III, W.J., Gustin, D.J., Roush, W.R., (2005) J. Am. Chem. Soc., 127, p. 5770Cowden, C.J., Paterson, I., (1997) Org. React., 51, p. 1Franklin, A.S., Paterson, I., (1994) Contemp. Org. Synth., 1, p. 317Heathcock, C.H., (1991) Comprehensive Organic Synthesis, 2, p. 181. , Heathcock, C. H., Ed.Pergamon Press: New YorkKim, E.M., Williams, S.F., Masamune, S., (1991) Comprehensive Organic Synthesis, 2, p. 239. , Heathcock, C. H., Ed.Pergamon Press: New YorkPaterson, I., (1991) Comprehensive Organic Synthesis, 2, p. 301. , Heathcock, C. H., Ed.Pergamon Press: New YorkBraun, M., (1987) Angew. Chem., Int. Ed. Engl., 26, p. 24Heathcock, C.H., (1984) Asymmetric Synth., 3, p. 111Evans, D.A., Nelson, J.V., Taber, T.R., (1982) Top. Stereochem., 13, p. 1Paterson, I., Goodman, J.M., (1989) Tetrahedron Lett., 30, p. 997Paterson, I., Florence, G.J., (2000) Tetrahedron Lett., 41, p. 6935Evans, D.A., Coleman, P.J., Côté, B., (1997) J. Org. Chem., 62, p. 788Evans, D.A., Trotter, B.W., Coleman, P.J., Côté, B., Dias, L.C., Rajapakse, H.A., Tyler, A.N., (1999) Tetrahedron, 29, p. 8671Paterson, I., Collett, L.A., (2001) Tetrahedron Lett., 42, p. 1187Paterson, I., Gibson, K.R., Oballa, R.M., (1996) Tetrahedron Lett., 37, p. 8585Tanimoto, N., Gerritz, S.W., Sawabe, A., Noda, T., Filla, S.A., Masamune, S., (1994) Angew Chem., Int. Ed. Engl., 33, p. 673Roush, W.R., Bannister, T.D., Wendt, M.D., Jablonowski, J.A., Scheidt, K.A., (2002) J. Org. Chem., 67, p. 4275Arefolov, A., Panek, J.S., (2002) Org. Lett., 4, p. 2397Roush, W.R., Bannister, T.D., Wendt, M.D., Vannieuwenhze, M.S., Gustin, D.J., Dilley, G.J., Lane, G.C., Smith III, W.J., (2002) J. Org. Chem., 67, p. 4284Oikawa, Y., Yoshioka, T., Yonemitsu, O., (1982) Tetrahedron Lett., 23, p. 889noteHeathcock, C.H., Pirrung, M., Sohn, J.E., (1979) J. Org. Chem., 44, p. 4294not