Base-isolated

At first, the dimeric nature of the base isolated from 3-ethyl-2-methyl-4-phenylthiazolium was postulated via a chemical route. Indeed the adduct of ICH, on a similar 2-ethylidene base is a 2-isopropylthiazolium salt in the case of methylene base it is an anilinovinyl compound identified by its absorption spectrum and chemical reactivity (45-47). This dimeric structure of the molecule has been definitively established by its NMR spectrum. It is very similar to the base issued from 2.3-dimethyl-benzo thiazolium (48). It corresponds to 2-(3 -ethyl-4 -phenyl-2 -methylenethiazolinilydene)2-methyl-3-ethyl-4-phenylthiazoline (13). There is only one methyl signal (62 = 2.59), and two series of signals (63= 1.36-3.90, 63= 1.12-3.78) correspond to ethyl groups. Three protons attributed to positions T,5,5 are shifted to a lower field 5.93, 6.58, and 8.36 ppm. The bulk of the ten phenyl protons is at 7.3 ppm (Scheme 22). 

Kumar, A. and Basu, S. Isolation iti a shake table system . Workshop Proceedings on Base Isolation, New Delhi, June, (1989). 

Nicotelline, CjoHgNj. This base, isolated by Pictet and Rotschy, forms colourless needles, m.p. 147-8°, b.p. above 300° its aqueous solution is neutral to litmus. Unlike other tobacco bases it yields a sparingly soluble, crystalline dichromate. It does not decolorise acid permanganate, and appears not to be a pyrrole derivative. ... 

MethyHsopelletierine, CgHj,ON. This base, isolated by Piccinini under the name fsomethylpelletierinc, was re-examined by K. Hess ei al. It is an oily alkaline liquid, b.p. 114-7°/26 mm., miscible with water and optically inactive. The hydrochloride has m.p. 156° hydrobromlde, m.p. 151-2° the picrate melts at 158° and the aurichloride forms orange-yellow rosettes, m.p. 115-7°. The base can be resolved into d- and... 

Acutumine, C20(ai)H87OgN. This base, isolated by Goto and Sudzuki,... 

The methylation of 51.4 parts by weight of D,L-3-hydroxy-N-methyl-morphinan is carried out with a methylating solution obtained from 51.5 parts by weight of phenyl-trimethyl-ammonium-chloride. The D,L-3-methoxy-N-methyl-morphinan is isolated in the form of its hydrobromide, which melts with 1 mol of water at 92°-94°C, without water at 239°-240°C. The base isolated from the aqueous solution by means of sodium carbonate melts at 81°-83 C. 

The peptide sequences obtained for codeinone reductase aligned well with the amino acid sequences for 6 -deoxychalcone synthase (chalcone reductase) from alfalfa, Glycerrhiza, and soybean. Knowledge of the relative positions of the peptides allowed for a quick RT-PCR based isolation of cDNAs encoding codeinone reductase from P. somniferum. The codeinone reductase isoforms are 53 % identical to chalcone reductase from soybean.25 By sequence comparison, both codeinone reductase and chalcone reductase belong to the aldo/keto reductase family, a group of structurally and functionally related NADPH-dependent oxidoreductases, and thereby possibly arise from primary metabolism. Six alleles encoding codeinone... 

Mechanism-Based Isolation and Structures of Some Anticancer Active Natural Products... 

Metoprolol Metoprolol, l-(wo-propylamino)-3-[4 (2-methoxyethyl)phenoxy]-2-propanol (12.1.5), is synthesized by reacting 4-(2-methoxyethyl)phenol with epichlorhy-dride in the presence of a base, isolating l,2-epoxy-3-[4 (2-methoxyethyl)phenoxy] propane (12.1.4), the subsequent reaction of which, analogous to that described before, with jio-propylamine, gives an opening of the epoxide ring and leads to the formation of metoprolol (12.1.5) [7,8]. 

A tertiary base isolated from Thalictrum strictum was assigned a pavine structure based on the spectral data (27). Three methoxyl and one methylenedioxy functions were detected with the aid of mass spectroscopy. Structure 3 was proposed as the most probable representation for this new pavine alkaloid, which indeed is the first example of a pentasubstituted pavine base. However, when the reported aromatic proton chemical shifts (8 6.23, 6.36, and 6.54) were evaluated in the light of empirical rules about the H-NMR absorptions of pavine bases (Section V,B), and it seemed possible that the two upfield absorptions belong to H-4 and H-10 rather than to H-1 and H-10. Therefore, alternative structure 4 cannot presently be completely excluded from consideration. 

DC018 Gambhir, S. S., A. K. Sanyal, S. P. Sen, and P. K. Das. Studies on Daucus carota. Part II. Cholinergic activity of the quaternary base isolated from water-soluble fraction of alcoholic extract of seeds. Indian J Med Res 1966 54 1053. 

Wang, S., Roy, N.S., Benraiss, A., Goldman, S.A. (2000). Promoter-based isolation and fluorescence-activated sorting of mitotic neuronal progenitor cells from the adult mammalian ependymal/subependymal zone. Dev Neurosci, 22, 167-76. 

An analagous process for isolating and concentrating portions of a sample is the use of thin layer chromatography. Here, however, it is common practice, in the treatment of an unknown sample, to place a known standard on the same plate and to run the two systems parallel so that differences in performance of an adsorbing system from one laboratory to another are accounted for by basing isolation of the desired components from the plate on the determined position of the known standard, run on the same plate. The normally limited capacity of thin layer chromatographic systems tends to exclude their wide use for the combined isolation-concentration steps of trace analysis, but circumstances in which this technique may be useful should not be overlooked. ... 

Where zinc and tin are used, double salts of the general formula, R.XH2.HC1.MC12, sometimes separate out when the reduction is complete. These salts may be decomposed by excess of caustic soda, and the base isolated as before. 

TLC separation and densitometric determinations of alkaloids of Cyclea densi-flora, Stephania herbacea, S. brachandra, and S. tetrandra have been described the bis bases isolated were isochondodendrine, curine, berbamine, cycleanine, cepharanthine, curarine, fangchinoline, homoaromoline, isotetrandrine (= iso-sinomenine A), and tetrandrine (= sinomenine A) (330a). A TLC-densitometric method for assay of dauricine from biological specimens has been reported (331). Tubocurarine served as a test case for pseudophase liquid chromatogra-... 

Burgess, R. M., and S. A. Ryba. 1998. A comparison of colloid-contaminant C18 based isolation techniques using PCB contaminated humic substances and interstitial water. Chemosphere 36 2549. 

Isocorydine (1,2,10-trimethoxy-ll-hydroxyaporphine) was isolated for the first time by Maranon (422) and Go (423). Reynolds el al. (401) reported that its effect resembled that of bulbocapnine. Administration of N-methylisocorydinium chloride, a quaternary base isolated from Fagaro coco, results in apnea and finally in cardiac failure (424r-426). In rabbits it causes an increase in excitability whereas in rats it causes a decrease. The effect of mesantoine and coramine is to some extent antagonistic, which is contrary to the effect of lobeline and of the barbiturates. In rabbits and toads isocorydine diminishes the contractility and excitability of the skeletal muscles however, a curarelike effect was not observed. After intraperitoneal application to rats the recorded LD50 was 10.9 mg/kg. 

A variation of the Schmidt type reaction is the rearrangement of an azidocyc-loalkane, which is formed from the addition of hydrazoic acid to an cycloalkene. This reaction was used in the synthesis of muscopyridine (II/U4), a base isolated from the perfume gland of the musk deer [85]. In this context the reaction of II/115 as a model compound under the conditions of the Schmidt reaction gave a mixture of two compounds which after dehydrogenation yielded 11/116 and 11/117. The mechanism can be explained in terms of the migration of different bonds in the precursor. 

Gelseverine, C21H24-26N2O3, is the tertiary base isolated from the minor alkaloids of Gelsemium sempervirens. It has not yet been obtained crystalline but can be characterized as its perchlorate, mp 250°-252°, or methiodide, mp 259°-261°. The molecule contains one methylimino group and two methoxyl groups, but no C -methyl groups. The UV- and IR-spectra are consistent with its formulation as a 1,3,3-trisubstituted oxindole derivative (18). 

The early chemistry of the alkaloids of Alstonia species is characterized by confusion and colored by an acrimonious dispute between the two principal protagonists concerning the constituents of A. scholaris. Most of the bases isolated from this and other species were at best ill-defined and uncharacterized, and their identity and status as individual alkaloids are open to question it is probable that several of the substances obtained were simply the same alkaloid in different states of purity. 

B. L. Iverson. Function-based isolation of novel enzymes from a large library. Nat Biotechnol (2000) 18(10) 1071-4. 

The differences reflected in the two methods indicate the presence of amphoteric asphaltene compounds, an observation that is at odds with that reported by Sternberg et al. (7) for asphaltenes from the Synthoil process. The bases isolated by this ion exchange method correspond closely in amount to those isolated by the phosphotungstic acid scheme. 

Olsen Ml, Stephens D, Griffiths D, Daugherty P, Georgiou G, Iverson BL. Eunction-based isolation of novel enzymes from a large Ubrary. Nat. Biotechnol. 2000 18 1071-1074. 

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