Aliphatics, cyclic forms

Compounds 1-10. c-x " c-x represent 05 and Cl of cyclic and acyclic carbohydrate, respectively, in which the carbohydrate moiety may be any mono or oligosaccharide, a or ano-mer (cyclic forms) C Hjn+, is a saturated aliphatic chain, while alkyl maybe either a saturated or an unsaturated aliphatic chain... 

Diamines.1 The cyclic sulfate (2) of (R,R)-stilbenediol (1) reacts with benzamidine (3) in refluxing DME to form the imidazoline 4 as a single enantiomer. This product is converted by known steps into (S,S)-stilbenediamine (5) in 44% yield. The overall process involves inversion of both stereogenic centers of 1. The transformation was applied to several aliphatic cyclic sulfates and shown to afford 1,2-diamines in high percent ee. 

S l substitution of different compounds by nitronate anions followed by elimination of nitrous acid is a good method for the synthesis of various substituted olefins. A clear example is the base-promoted HN02 elimination from the C-alkylation products formed by the S l reaction between 2-chloromethyl-3-nitroimidazo[l,2-a]pyridine (11) and various aliphatic, cyclic and heterocyclic nitronate anions87, affording new potential pharmacological derivatives with a trisubstituted double bond at the 2-position. A representative example is shown in equation 32. 

According to this decomposition mode, carbon should be in the deposit in an aliphatic or carbidic form, due to the more or less complete decomposition of C H. The condensed cyclic form is less probable by this mechanism unless... 

The authors also examined coal and wood particles within the sediment. They found a larger concentration of PAH within these particles compared to the silica particles. They also determined that while organic carbon molecules were present uniformly throughout these particles in mixtures of aliphatic and aromatic (cyclic) forms, the PAH was concentrated at the surfaces of these particles. The conclusions derived from this powerful combination spectroscopies will allow a more successful approach to remediation of the Milwaukee Harbor. These results could also have a larger impact, since they show the feasibility of identifying chemical constituents and their distributions in sediments which are important in planning remediation efforts in different environs. 

Use of 3-pyrrohdine carboxylic acids (7.139) and (7.140) as catalysts results in formation of the anft -Mannich adduct as the major product. This reversal in diastereoselectivity arises from reaction of the s-cis conformer of the enamine formed from (7.139) or (7.140), as depicted in Figure 7.6. Catalyst (7.139) provides high ees in the anfr-Mannich reaction of aliphatic cyclic and acyclic ketones such as pentan-3-one (7.141) while the methyl-substituted analogue (7.140) catalyses the anti-addition of a range of aliphatic aldehydes in 98 to >99%... 

A very interesting reaction of hydrazoic acid with unsaturated aliphatic or cyclic compounds is referred to in a patent according to which aliphatic compoimds form Schiff s bases in high yields. From amylene... 

However, certain additives can decrease the rate of thermal decomposition [28]. These additives include cyclic sulfates, sulfones, sultones, aliphatic and aromatic anhydrides, and polymers with pendant carboxylic acid functional groups. Most of these materials are latent acids, which decompose on heating in the presence of moisture to form a strong acid, as shown for cyclic sulfate, 9, in Eq. 5. 

Polyfluorinated a-diketones react with 1,2-diainino compounds, such as ortlio-phenylenediamine, to give 2,3-substituted quinoxalmes [103] Furthermore, the carboxyl function of trifluoropyruvates offers an additional electrophilic center. Cyclic products are obtained with binucleophiles [13, 104] With aliphatic or aromatic 1,2-diamines, six-memhered heterocycles are formed Anilines and phenols undergo C-alkylation with trifluoropyruvates in the ortho position followed by ring closure to form y-lactams and y-lactones [11, 13, 52, 53, 54] (equation 23). 

The next seven references are cited not because of the experimental procedures described but because they indicate diversification in the types of enamines prepared and studied. Both Paquette (25) and Kasper 26) have condensed 2,5-methylene-l,2,5,6-tetrahydrobenzaldehyde (5-nor-bornene-2-carboxyaldehyde) (2) with several cyclic and open-chain aliphatic secondary amines. Kasper studied the ratio of endo to exo aldehyde formed upon hydrolysis of these enamines and the dihydro enamines. Paquette investigated the addition of sulfene to the enamines. -Fluoro-... 

Enklaar has showil that when citral is reduced by metals in a stream of hydrogen, it yields not only reduced aliphatic compounds, but that the ring is also closed, and a series of cyclic compounds is also formed. 

Although the enantioselective intermolecular addition of aliphatic alcohols to meso-epoxides with (salen)metal systems has not been reported, intramolecular asymmetric ring-opening of meso-epoxy alcohols has been demonstrated. By use of monomeric cobalt acetate catalyst 8, several complex cyclic and bicydic products can be accessed in highly enantioenriched form from the readily available meso-epoxy alcohols (Scheme 7.17) [32]. 

Aliphatic disulfides are not thought to be effective as initiators in this context. However, Endo et a . K have described the use of the cyclic 1,2-disulfides 11 and 12 as initiators in a controlled radical polymerization. Polymerization of S at 120 °C gave a linear increase in molecular weight with conversion and the PS formed was used as a macroinitiator to form PS-6/oet-PMMA. The precise mechanism of the process has not been elucidated. 

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