Barbas studies

Perricone NV (1993) Treatment of pseudofolliculitis barbae with topical glycolic acid a report of two studies. Cutis 52(4) 232-235... 

More recently, asymmetric Mannich-type reactions have been studied in aqueous conditions. Barbas and co-worker reported a direct amino acid catalyzed asymmetric aldol and Mannich-type reactions that can tolerate small amounts of water (<4 vol%).53 Kobayashi found that a diastereo- and enantioselective Mannich-type reaction of a hydrazono ester with silyl enol ethers in aqueous media has been successfully achieved with ZnF2, a chiral diamine ligand, and trifluoromethanesul-fonic acid (Eq. 11.31).54 The diastereoselective Mannich-type reaction... 

Marin A, Lopez-Gonzalvez A, Barbas C. Development and validation of extraction methods for determination of zinc and arsenic speciation in soils using focused ultrasound application to heavy metal study in mud and soils. Anal. Chim. Acta 2001 442 305-318. 

N-terminal L-proline, again in DMSO as solvent [40], In this study the maximum ee in the addition of acetone to trans-2-nitrostyrene was 31%. Alexakis and Andrey successfully employed the bis-pyrrolidine 52 as catalyst for the addition of aldehydes and ketones to trans-fi-nitrostyrene [41], whereas Barbas and Betancort [42] were able to perform the Michael addition of unprotected aldehydes to nitroolefins using the pyrrolidine derivative 53 as catalyst (Scheme 4.24). 

In the study by Alexakis, unsymmetrical ketones (e.g. 2-butanone) yielded mixtures consisting of regioisomers and syn/anti diastereomers with ee of the predominant syn isomers not exceeding 51%. For 3-pentanone and cyclohexanone (Scheme 4.24) Barbas et al. also used the related (S)-l-(pyrrolidinylmethyl)-pyrrolidine 54 to catalyze the addition of ketones to alkylidene malonates (Scheme 4.25) [43],... 

The substrate range scope and limitations Promising prospects for synthetic applications of the proline-catalyzed aldol reaction in the future were opened up by experimental studies of the range of substrates by the List [69, 70a, 73] and Barbas [71] groups. The reaction proceeds well when aromatic aldehydes are used as starting materials - enantioselectivity is 60 to 77% ee and yields are up to 94% (Scheme 6.19) [69, 70], The direct L-proline-catalyzed aldol reaction proceeds very efficiently when isobutyraldehyde is used as substrate - the product, (R)-38d, has been obtained in very good yield (97%) and with high enantioselectivity (96% ee). 

This reaction is particularly suitable for the preparation of the Wieland-Miescher ketone 96, a very useful building block for construction of a broad variety of biologically active compounds such as steroids, terpenoids, and taxol. On the basis of the proline-catalyzed approach described above Barbas et al. recently reported an optimized procedure for formation of the chiral Wieland-Miescher ketone, 96 [105]. It has been shown that this synthesis (which comprises three reactions) can be performed as a one-pot synthesis. The desired product is obtained in 49% yield with enantioselectivity of 76% ee (Scheme 6.43). Here L-proline functions as an efficient catalyst for all three reaction steps (Michael-addition, cydiza-tion, dehydration). It is also worth noting that although many other amino adds and derivatives thereof were tested as potential alternative catalysts, L-proline had the best catalytic properties for synthesis of 96. This result emphasizes the superior catalytic properties of proline reported after previous comparative studies by the Hajos group [100, 101]. 

The prefrontal cortex (PFC) is the anterior part of the frontal lobes of the brain. It lies in front of the motor and premotor areas. The PFC is divided into the lateral, orbitofrontal, and medial prefrontal areas (Barbas and Pandya, 1987, 1989). Comprehensive reviews of this structure and functions of the PFC have been published in various forms (Fuster, 1997 Goldman-Rakic, 1987 Miller and Cohen, 2001 Passingham, 1993 Tanji and Hoshi, 2008). The PFC possesses a wealth of anatomical connectivity with multiple cortical and subcortical areas, and is involved in broad aspects of behavioral control. The PFC has been implicated in complex cognitive behaviors, social behaviors, and personality expression. Recent studies of this area have revealed its role in the control of a much broader spectrum of functions, such as cross-modal and cross-temporal association of information, in the executive control of behavior, and in the top-down control of neural networks involving the cortical and subcortical areas. Among them, the executive control of action was a term coined to capture various aspects of PFC function. 

To test this hypothesis, we created the first synthetic antibody libraries in 1992 (Barbas et al., 1992). In this study a repertoire of synthetic... 

Bahmanyar S, Houk KN (2001a) The origin of stereoselectivity in proline-catalyzed intramolecular aldol reactions. J Am Chem Soc 123 12911-12912 Bahmanyar S, Houk KN (2001b) Transition states of amine-catalyzed aldol reactions involving enamine intermediates theoretical studies of mechanism, reactivity, and stereoselectivity. J Am Chem Soc 123 11273-11283 Bahmanyar S, HoukKN, Martin HJ, ListB (2003) Quantum mechanical predictions of the stereoselectivities of proline-catalyzed asymmetric intermolec-ular aldol reactions. J Am Chem Soc 125 2475-2479 Barbas CF 3rd, Heine A, Zhong G, Hoffmann T, Gramatikova S, Bjoernstedt R, List B, Anderson J, Stura EA, Wilson I, Lemer RA (1997) Immune versus natural selection antibody aldolases with enzymic rates but broader scope. Science 278 2085-2092... 

Fig. 31.1. Pooled prevalence of rates for post-stroke dementia within three to six months of stroke in hospital-based studies that did not exclude pre-stroke dementia. Cl, confidence interval. Study sources Klimkowicz-Mrowiec et ol. (2006) Zhou et ol. (2004) Barba et ol. (2001) Tang et ol. 2004a,b) Pohjasvaara et ol. (1999) Desmond (2004) Henon et at. (1997, 2001).

After these studies were published. Professors Barbas and List independently contacted Houk, and the List collaboration developed. Houk remembers that List suggested Why don t you try the reaction of cyclohexanone plus ben-zaldehyde. We ll do the experiments but I won t tell you the results—so you can make a real prediction. And that s the way it developed. That took quite some time—3 to 4 months to do all the computations—since we had to predict something. That s a more arduous task than explaining something. We were concerned about missing a TS, so we went about a systematic search. And then we told List our results and there was really spectacular agreement. ... 

Strazzullo P, Barbato A Galletti F Barba G Siani A lacone R D Elia L Russo O Versiero M Farinaro E Cappuccio FP Abnormalities of renal sodium handling in the metabolic syndrome. Results of the Olivetti Heart Study J Hypertens. 2006 24 1633-1639. 

Quantitative conversion of 1-adamantanecarbonyl chloride to 1-adamantanecarbox-aldehyde has been accomplished by reduction of the acyl halide at carbon and mercury in MeCN containing TEAP [227]. Lozano and Barba [228] reduced 2-chloro-2-phenylacetyl chloride at mercury in methylene chloride containing TEACl and obtained derivatives of pyran-2-one and pyran-4-one. In subsequent work [229,230], these authors investigated the reduction of 2-bromo-2,2-diphenylacetyl bromide at graphite in methylene chloride containing TEABr and in the presence of inorganic sulfur compounds in the first study, a new sulfurated heterocyclic product was obtained ... 

Barba and colleagues have reported a fascinating study of the sources of lime for... 

Middleton, William D., Luis Barba, Alessandra Pecci, James H. Burton, Agustin Ortiz, LauraSalvini, Roberto Rodriguez Suarez. 2010. The Study of Archaeological Floors Methodological proposal for the Analysis of Anthropogenic Residues by Spot Tests, ICP-OES and GC-MS. Journal of Archaeological Method and Theory 17 183-208. 

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