Bistris

Clark et al. [81] determined the time course of A-acetylation of primaquine by Streptomyces roseochromogenous and Streptomyces rimosus by quantitative high performance liquid chromatographic analyses of the culture broths. The A-5-bistri-fluoroacetyl derivative of primaquine was used as an internal standard in the analysis for the quantitation of primaquine A-acetate in microbial culture broths. S. roseochromogenous forms the highest level of primaquine A-acetate at 24—36 h after substrate addition, while S. rimosus is slower in its acetylation, peaking at 3 days after substrate addition. The formation of a novel dimeric compound from the reaction of primaquine with 8-(4-phthalimido-l-methylbutylamino)-6-methoxy quinoline is also reported. 

An improved procedure for the selective alkylation of 2,4-quinazolinediones at the 1-position via the 2,4-bistri-methylsilyloxy derivatives has been developed <20030PD700>. This procedure enabled a large-scale synthesis of the aldose reductase inhibitor FK366 28 from the bistrimethylsilyloxy quinazoline 27 (Scheme 2). 

Ethylacetoacetic Acid Diazide, Ethyl-a,a-bistri-ozoacetoacetate or Diazidoethylacetoacetate,... 

SILYLATION Allyltrimethylsilane. Bistri-methylsilyl ether. 4-0-ButyldimethyE siiyloxy-3-pen tene-2-one. r-B u ty ldi-methyisilyl irifluoromethanesulfonate. Chloromethyldiphenylsilane. Chlorotrl-methylsilane. Hexamethyldisiloxane. 

Rates measured using the [I4C] glucose incorporation assay. Except for bistris, Kj values calculated from Dixon plots, assuming competitive inhibition. 

Similar to indirect absorbance detection, indirect fluorescence has been employed to detect MPA, EMPA, IMPA, and PMPA, using tetrakis(4-sul fopheny 1 iporphine (TSPP) as the indirect probe (19). A violet diode laser operating at 415nm was used for excitation. Using an electrolyte composed of 50 tM TSPP and 5mM [Bios(2-hydroxyethyl)-amino]tris-(hydroxymethyl)methane (Bistris) at pH 7.2 under normal polarity, baseline separation was achieved in less than 2 min. A limit of detection of 0.1 xM (9ppb) for MPA was achieved. 

Conjugation reagents Formamide (>99.5%, Fluka) BisTris HBr, ammonium acetate. HPLC columns are as for peptide and PNA syntheses and columns are immersed in a water bath (45°C) or surrounded by avery efficient heating jacket. 

FIGURE 12 Plots of the approach distance a (in angstroms) versus k for the protein human serum albumin (HSA) (pi = 5.85, Mr = 69,000) measured with the strong anion exchange sorbent, Mono-Q, under conditions of varying NaCI concentration to achieve smaller kf values at a flow rate of I mL/min and at a temperature of 298 K with (I) 20 mM piperazine buffer, pH 9.6 (2) 20 mM triethanolamine, pH 7.5 (3) bistris buffer, pH 6.5 and (4), 20 mM piperazine buffer, pH 5.5, as the eluents. Data selected from Ref. 542. 

A broadly applicable synthesis of benzol/-]furans by Warrener relies on DielsAlder/retro DielsAlder reactions with s-tetrazines. Using this methodology with 3,6-di(pyridin-2-yl)-i -tetrazine 162 the generation of an isolable 5,6-(bistri-methylsilyl)benzo[c]furan 163 has been achieved (Scheme 97) <2002T9413, CHEC-III(3.07.6)551>. 

Early attempts at producing dialkyltin compounds yielded polymers. More recently, Neumann has found several synthetic routes to reactive R2Sn intermediates which can be trapped by oxidative-addition reactions (J). In the absence of trapping agents the divalent tin compound polymerizes. Lappert and co-workers have shown that the bulky bistri-methylsilylmethyl ligand stabilizes the divalent tin species toward polymerization. This stable divalent tin species thus provides an excellent starting material for investigating a wide variety of oxidative-addition reactions, as shown in Fig. 10 (78). 

Figure 3 Effect of Zn + binding on the CD spectrum of the hemopexin (Hx)-heme complex the Hx-heme complex (thick black curve), additions of 3-15 equiv of Zn + (thin black curve), and addition of 18 equiv of Zn + (red curve). The Hx-heme concentration is 8 xM, with 50 mM bisTris buffer and 50 mM sodium chloride (pH 7.0, 25 °C). (Reprinted with permission from Mauk, Rosell, Lelj-Garolla, Moore and Mauk. 2005 American Chemical Society)...

TRIMETHYLSILYL ETHERS Bistri-methylsilyl ether. lodotrimethykilane. 

Several arylboronic acids have been examined in place of borane-THF to improve the Lewis acidity of 2 and the stereoselectivity [49b]. The boron substituent of 2 has a large effect on the chemical yield and the enantiomeric excess of the allylation adduct, and 3,5-bistrifluoromethylbenzeneboronic acid results in the greatest reactivity— when a complex which is easily prepared from a tartaric acid derivative and 3,5-bistri-fluoromethylbenzeneboronic acid in propionitrile at room temperature is used, the reactivity is improved without reducing the enantioselectivity. For instance, the reaction of l-trimethylsilyl-2-methyl-2-propene with benzaldehyde in the presence of only 10 mol % 2 proceeds to give 99 % yield and 88 % ee (Fig. 19). 

Bistri O, Lecourt T, Mallet J-M, Sollogoub M, Sinay (2004) Chem Biodiversity 1 129... 

Bistri O, Mazeau K, Auzely-Velty R, Sollogoub M (2007) Chem Eur J 13 8847... 

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