Alkoxy derivatives

Anomalous Fischer cyclizations are observed with certain c-substituted aryl-hydrazones, especially 2-alkoxy derivatives[l]. The products which are formed can generally be accounted for by an intermediate which w ould be formed by (ip50-substitution during the sigmatropic rearrangement step. Nucleophiles from the reaction medium, e.g. Cl or the solvent, are introduced at the 5-and/or 6-position of the indole ring. Even carbon nucleophiles, e.g. ethyl acetoacelate, can be incorporated if added to the reaction solution[2]. The use of 2-tosyloxy or 2-trifluoromethanesulfonyloxy derivatives has been found to avoid this complication and has proved useful in the preparation of 7-oxygen-ated indoles[3]. 

The most suitable synthetic method for these products is the heterocyc-lization reaction of N-thioacyl derivatives of amino acids (202) with phosphorus tribromide (378, 442-450, 559, 560) or anhydrous trifluoroacetic acid (448, 449, 451, 452) (Scheme 103). Treatment of N-thioacyl amino acids with acetic anhydride leads directly to the thiazolylacetate without isolation of an intermediate thiazolinone (365. 452). 2-Alkoxy-derivatives of A-2-thiazoline-5-one, however, can be obtained without acetylation by this method (453, 454). 

The thiazolium ring, as most heterocycloammoniums, is a Lewis acid conferring to the carbon atom in the 2-position the carbocationic property of adding the free pair of a base either organic or mineral that may be the molecule of solvent as ROH (Scheme 11). For many nuclei of suitable acidity, these equilibria can be observed in dilute solution by means of absorption spectra when species A and C possess different characteristics (24). For example, benzothiazolium and benzoxazolium in methanol and ethanol give at 10 mole liter 8 and 54% of the alkoxy derivatives for the former and 29 and 90% for the latter respectively. 

Ethers are named m substitutive lUPAC nomenclature as alkoxy derivatives of alkanes Functional class lUPAC names of ethers are derived by listing the two alkyl groups m the general structure ROR m alphabetical order as separate words and then adding the word ether at the end When both alkyl groups are the same the prefix di precedes the name of the alkyl group... 

Alkyl hahdes in the presence of silver oxide react with alkyl malates to yield alkoxy derivatives of succinic acid, eg, 2-ethoxysuccinic acid, H00CCH2CH(0C2H )C00H (12,13). A synthetic approach to produce ethers of malic acid is the reaction of malic esters and sodium alkoxides which affords 2-alkoxysuccinic esters (14). 

Simple ethers derive their name from the two groups attached to the oxygen followed by the word ether, eg, diethyl ether, CH3CH2OCH2CH3. Eor symmetrical ethers the "di" prefix is often omitted. If one group has no simple name, the compound may be named as an alkoxy derivative, eg, 2-ethoxyethanol, CH3CH2OCH2CH2OH. 

The 5,6-amide function has been found to be unusually reactive in the 2,4-disubstituted pteridin-6-one series, forming the corresponding 6-alkoxy derivatives, e.g. (141), with alcoholic HCl directly (62CB755, 70CB735). 

These a-acylaminoketones also provided a convenient synthesis of thiazoles on treatment with phosphorus pentasulfide (Gabriel s method). Although yields range from 45 to 80%, substituents are usually restricted to alkyl, aryl and alkoxy derivatives. Thus, reaction of the a-acylaminoketone (4) with P4S1Q gave the thiazole (5), and thiazole (7) itself was prepared in this manner in 62% yield from formylaminoacetal (6) (14CB3163). The corresponding 5-ethoxy compound was obtained from the a-formamidoester and phosphorus pentasulfide in an inert solvent. 

Section 16.1 Ethers are compounds that contain a C—O—C linkage. In substitutive lUPAC nomenclature, they are naned as alkoxy derivatives of alkanes. In functional class lUPAC nomenclature, we name each alkyl group as a separate word (in alphabetical order) followed by the word ether. 

The formation of quaternary salts by attack at an oxygen atom is only achievable in certain special cases. Most of the attempts to effect reactions of this type with N-alkyl-a-oxo derivatives have failed. Until recently it might have been assumed that 2-alkoxy-quaternary salts were unobtainable, the usual product from reactions with the alkoxy derivatives being the N-alkyl-oxo compounds (see Section IV,C). Recently, however, Meerwein and his co-workers found that triethyloxonium borofluoride and a number of N-methyl-a-oxo... 

In the presence of potassium carbonate, alkyl halides reacted with the imidic acid tautomers 154 of l,2,4-triazolo[l,5-c]pyrimidin-2-ones (153) to afford the 2-alkoxy derivatives 155 (85USP4528288 94JMC2371) (Scheme 60). 

Recently, polyimines include the synthesis of long alkoxy (Cg-Cig) side chain derivatives [188,189], which are presumably soluble to some extent in organic solvents and derivatives containing fluorene cardo unit [190]. Trifluoromethyl groups [191] in the polymer backbone provide solubility in organic solvents. Studies of the electrical conductivity of doped conjugated aromatic polyimines and alkoxy derivatives have been reported [188], and the values are in the range of 10 to 10 S/ cm. 

PPV and its alkoxy derivatives are /j-type conductors and, as a consequence, hole injection is more facile than electron injection in these materials. Efficient injection of both types of charge is a prerequisite for efficient LED operation. One approach to lowering the barrier for electron injection is the use of a low work function metal such as calcium. Encapsulation is necessary in this instance, however, as calcium is degraded by oxygen and moisture. An alternative approach is to match the LUMO of the polymer to the work function of the cathode. The use of copolymers may serve to redress this issue. 

Nucleophilic addition to a, -unsaturated sulfones has long been known. For example, treatment of divinyl sulfone with sodium hydroxide has been known to afford bis( -hydroxyethyl) sulfone "", while the reaction of a- and -naphthyl allyl sulfones and allyl benzyl sulfone " with alkali hydroxide or alkoxide gave -hydroxy or alkoxy derivatives. In the latter reaction, the allyl group underwent prototropy to the 1-propenyl group, which in a subsequent step underwent nucleophilic attack . Amines, alcohols and sulfides are known to add readily to a, -unsaturated sulfones, and these addition reactions have been studied widely. In this section, the addition of carbon nucleophiles to a, ji-unsaturated sulfones and the reactions of the resulting a-sulfonyl carbanions will be examined. 

The Mukaiyama aldol reaction can provide access to a variety of (3-hydroxy carbonyl compounds and use of acetals as reactants can provide (3-alkoxy derivatives. The issues of stereoselectivity are the same as those in the aldol addition reaction, but the tendency toward acyclic rather than cyclic TSs reduces the influence of the E- or Z-configuration of the enolate equivalent on the stereoselectivity. 

There are also useful intramolecular functionalization methods that involve hydrogen atom abstraction by oxygen radicals. The conditions that were originally developed involved thermal or photochemical dissociation of alkoxy derivative of Pb(IV) generated by exchange with Pb(OAc)4.374 These decompose, giving alkoxy... 

AMINO ACID DERIVATIVES, [NP(NHCH3)2]n MIXED SUBSTITUENT ARYLAMINO AND ALKOXY DERIVATIVES POLYMERIZATION OF ORCANO-HALO TRIMERS POLYMER-BOUND DYES... 

The compound (originally reported as tetramethylplatinum) and usually obtained in admixture with an alkoxy derivative, detonates on heating. 

The diastereomerically pure chlorides 73a and 73b afforded the corresponding P-substitution products on reaction with nucleophiles. Thus 73a and 73b could be converted readily into the corresponding alkoxy-derivatives on treatment with an alcohol in the presence of triethylamine and into aryloxy-derivatives upon treatment with the sodium salt of the appropriate phenol at room temperature. Replacement of chlorine by an alkoxy- or aryloxy-group occurred with retention of configuration, e.g., 73a gave 74a, 75a, and 76a. Similarly, 74b and 75b could be obtained from 73b (Scheme 24) [32, 38, 54],... 

A series of hydroxy-, alkoxy-, and phenoxyfurazans and difurazanyl ether derivatives 184 were synthesized by reactions of mono- and dinitrofurazans 183 with O-nucleophiles. The effect of the furazan nature and reactant ratio on the structure of products has been discussed <1999RJ01525>. In this way, the nitro group has been replaced by alkoxy derivatives (Equation 33) <2000BMC1727>. 

Hydroxy and 3-hydroxy-5-alkoxy derivatives 124 are afforded by the oxidation of iminodicarbonates 123 with... 

Kato, K. Zheng, C. Dey, S. K. Torii, Y. 1997. Chemistry of the alkoxy-derived precursor solutions for layer-structured perovskite thin films. Int. Ferro. 18(l-4) 225-235. 

The mesylate derivatives of nonracemic a-hydroxy stannanes undergo S/y 2 displacement by alkoxides to afford the inverted a-alkoxy derivatives (equation 31)70. 

Moreover, there are several patents and reports on cephalosporins and 7-alkoxy derivatives thereof, which are characterized by a pyridazine-derived substituent attached to the thiazine ring. Some typical examples are given in formulae (126) [347-356], (127) [357], (128) [358], (129) [359, 360] and (130) [355, 361-363] in which R1 represents a variable acyl group. 

Fig. 27 Reaction coordinates for six axial aryl tetrahydropyranyl acetals [96] normalized on to a common scale (see the text) and superimposed on the reaction coordinate for a parent alkoxy derivative (broken curve). Reprinted with permission from Jones and Kirby (1984). Copyright 1984 American Chemical Society.

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