Derivatives preparation

C3N3CJ3. M.p. 154X, b.p. 190X. Cyclic derivative prepared by polymerization of CICN... 

An important method for construction of functionalized 3-alkyl substituents involves introduction of a nucleophilic carbon synthon by displacement of an a-substituent. This corresponds to formation of a benzylic bond but the ability of the indole ring to act as an electron donor strongly influences the reaction pattern. Under many conditions displacement takes place by an elimination-addition sequence[l]. Substituents that are normally poor leaving groups, e.g. alkoxy or dialkylamino, exhibit a convenient level of reactivity. Conversely, the 3-(halomethyl)indoles are too reactive to be synthetically useful unless stabilized by a ring EW substituent. 3-(Dimethylaminomethyl)indoles (gramine derivatives) prepared by Mannich reactions or the derived quaternary salts are often the preferred starting material for the nucleophilic substitution reactions. 

The 2-anilinoselenazoles follow an analogous reaction path. The entry of bromine into the 5-position is in agreement as seen in Scheme 35. The 2-anilino-4-phenylselenazole gives a 5-bromo derivative by bromination. It is not identical with either of the bromo derivatives prepared by direct synthesis (Scheme 35) (99). 

Chemical Properties and Derivatives, There have been thousands of rifamycin derivatives prepared in an attempt to obtain a broader... 

Stmcture (72) exemplifies the C-4 derivatives prepared by these routes. From this class of monobactams, RU-44790 [110012-78-7] (72, R = FI, =... 

Dithiepin derivatives prepared in high yield from 1,2-bis(mercaptomethyl)ben-zenes, are cleaved by HgCl2 (80% yield). Neither reagents nor products have unpleasant odors. ... 

The substituted methylene derivative, prepared from a 2-formylpyrrole and a ma-lonic acid derivative, was used in a synthesis of chlorophyll. It is cleaved under drastic conditions (coned alkali). ... 

This derivative, prepared from an amino acid and the acyl azide, is selectively cleaved in 80% yield by chymotrypsin. ... 

A -Nitroso derivatives, prepared from secondary amines and nitrous acid, are cleaved by reduction (H2/Raney Ni, EtOH, 28°, 3.5 h CuCl/concd. HCl"). Since many V-nitroso compounds are carcinogens, and because some racemization and cyclodehydration of V-nitroso derivatives of V-alkyl amino acids occur during peptide syntheses, V-nitroso derivatives are of limited value as protective groups. 

Typical perfluoroalkylated aromatic derivatives prepared via this type of reaction are illustrated in Table 6. This methodology has been used for the preparation 5-(perfluoroalkyl)pyrimidines [194], heptafluoroisopropylated aromatics... 

The DNP derivative, prepared from 2,4-dinitrofluorobenzene is released from the nitrogen with an anionic ion exchange resin." When used for histidine protection, the DNP group has been observed to migrate to nearby [ysine residues during Fmoc cleavage. ... 

The numerous 6-substituted 3-thioxo-5-oxo derivatives prepared by earlier authors are reviewed by Erickson et ak Subsequently a number of alkyl, and further 4-acetaminophenyl, 2-thienyl, 4-pyridyl," 4-antipyryl, " and 2-aminoethyP derivatives were prepared plus some others mentioned in the section on the synthesis of 6-azauracil. 

Angier and Marsico followed the course of alkylation first. The 7-dimethylamino-5-methylmercapto derivative reacted with dimethyl sulfate in an alkaline medium to yield a mixture of the 2- and 3-methyl derivatives. The reaction of the 7-diraethylamino derivative with ethyl iodide in an alkaline medium led to a mixture of all three possible monoethyl derivatives. The position of the alkyl group in all these substances was defined by comparing the UV spectra with derivatives prepared by a straightforward synthesis. After reacting the mercuric salts with tri-0-benzoylribofuranosyl chloride, they demonstrated the ribose residue to be bound in position 2. The same structure was shown to be valid for the derivative prepared by Andrews and Barber. ... 

The mass spectra of methyl 3-deoxy-p-v-tkreo-pentopyrano-side, methyl 4-deoxy-j3-T>-thieo-pentopyranoside, and 5-deoxy-fi-D-xylo-furanoside are discussed and compared fragmentation paths are sufficiently different to allow identification on the basis of their mass spectra. On the other hand, the mass spectra of methyl 2- and 3-deoxy-5-O-methyl-f3-i>-erythro-pentofuranosides do not exhibit fragmentation differences. The mass spectra of 3-deoxy-l,2 5,6-di-O-isopropylidene -d-xylo - hexofuranose, 5- deoxy -1,2-0-isopropylidene-D-xy o-hexofuranose, and 6-deoxy-l,2-0-iso-propylidene-D-glucofuranose show prominent differences, even between the 5- and 6-deoxy isomers. The interpretation of the spectra was aided by metastable-ion peaks, mass spectra of DzO-exchanged analogs, and the mass spectrum of an O-isopropylidene derivative prepared with acetone-d6. 

In liquid chromatography, in contrast to gas chromatography [see Section 9.2(2)], derivatives are almost invariably prepared to enhance the response of a particular detector to the substance of analytical interest. For example, with compounds lacking an ultraviolet chromophore in the 254 nm region but having a reactive functional group, derivatisation provides a means of introducing into the molecule a chromophore suitable for its detection. Derivative preparation can be carried out either prior to the separation (pre-column derivatisation) or afterwards (post-column derivatisation). The most commonly used techniques are pre-column off-line and post-column on-line derivatisation. 

Chlorotrifluoroethylene was converted in one step using nBuLi to dieth-ylfluoromalonate, which was a useful precursor for 5-fluorouracil (84CL1573). Fluorinated pyrimidinones can also be obtained from a,fi-unsaturated carboxylic acid derivatives prepared from 1-phosphonyloxy-perfluoroalkyl-l-alkenephosphonates (86TL2879). 

Allylboronates prepared from simple diols display appreciable reactivity, but eyelie boronate derivatives prepared from 1,2- or 1,3-diols display considerably less. The commonly employed pinacol esters are among the least reactive members of this class. 2-Allyl-3-methyl-l,3,2-oxaza-... 

Scheme 9.—Fragmentation in the mass spectrometer of an ethylthio derivative prepared from pyra-mine.

The TMAHP-MGX isolated from cationized aspen sawdust was reported to be applicable as a beater additive it significantly increased the tear strength of bleached spruce organosolv pulp [3]. The TMAHP derivatives prepared from isolated xylans were shown to improve the paper-making properties and... 

The trivalent [P04] and [As04] ions react similarly. Examples of anions that give insoluble Hg(I) compounds in this way include halides, pseudohalides, halates, carboxylates and sulfate. A trace of HNO3 or HCIO4 is often added to the solution of the Hg(I) nitrate or perchlorate to prevent disproportionation induced by alkali. Table 1 lists common Hg(I) derivatives prepared in this way and includes values of the solubility products of the sparingly soluble Hg(I) compounds where these are measured. A similar reaction is used to prepare HgjCO, from a soluble bicarbonate ... 

An a-fluorinated phosphinyl sulfoxide derivative, prepared as a mixture of diastereomers by the treatment of lithiated (a-fluoromethyl)diphenylphosphine oxide with menthyl p-toluenesulfinate, has been used for the preparation of enan-tiomerically pure 1-fluorovinyl and 1-fluoromethyl sulfoxides [76]. (E)-Diethyl ferf-butylsulfinylmethylphosphonate 117 has been prepared by the sulfinylation... 

Treatment of 41b with bromocyanide (BrCN) at 70 °C for 3 h afforded the amino compound 53 (76%). The structures of all the newly synthesized compounds were confirmed by the H, NMR, and mass spectra. Compounds 55 and 52 were identified by the homo- and heteronuclear spectra, as well as from comparison to the 1,2,4-triazolo-azipene derivatives prepared previously [22] (Scheme 10). 

---