Allylic methylene group

For the oxidation of allylic methylene groups (C=C-CH2 C=C-C=0), see Section 170 (Ketones from Alkyls and Methylenes). 

Because of the small amount of natural anandamide available, we were able to record H NMR spectra only. The peaks attributed to double-bond protons (5 5.30 to 5.45, multiplet) were coupled with those of protons that have the chemical shifts of doubly allylic protons (5 2.75 to 2.90, multiplet). Such doubly allylic protons are typically found in all-af, nonconju-gated polyunsaturated fatty acids such as linoleic and arachidonic acids. Three pairs of protons were observed between 5 2.01 and 2.27, which we attributed to two allylic methylene groups and one methylene group a to a carbonyl moiety. Only one methyl group was observed (0.99, triplet). The peaks observed for two protons at 3.42 (N-CH2, triplet), two protons at 3.72 (O-CH2, triplet), and two protons at 2.20 (COCH2, triplet) were... 

Very special amphiphilic properties of a divalent sulfur atom is witnessed in the reaction of a-thiomethylenecycloalkanones with acrylic esters under basic conditions [141]. The donor character of the allylic methylene group is enhanced by the sulfur (acting as an acceptor), yet the Michael cyclization that follows would be facilitated by a donor at that position. 

The redox catalyst [(trpy)(bpy)RuO]2 + jj oxidize allylic methylene groups... 

Experimental work in the area has thus far been limited to a few annulated members of the family. The benzo derivatives shown in 15-17 were recently synthesized for such a study, and the base-catalyzed exchange rates of their key allylic methylene groups were determined and compared to those of models 18-20 measured under comparable conditions.23 In each instance, the kinetic acidity of the C-H link was found... 

The 1II NMR corroborates diis conclusion since two vinyl protons are observed both in the reactant and product however, a new two-proton doublet appears at 4.155 for die newly produced allylic methylene group. The acid O-H proton is moved far upheld as well. The coupling constants of die vinyl protons (./ = 16 Hz) show the starting compound to be dans, and die large splitting for the downheld vinyl doublet of die product (J = 16 Hz) shows die trails stereochemistry to be maintained in die unsaturated alcohol product. Moreover die splitting between the methylene group and the upheld vinyl proton clearly supports its allylic position. 

Optically active sulfonimidamides react with benzylic and allylic methylene groups to give the formal product of nitrene CH insertion.75 The reaction is catalysed by dirhodium complexes and delivers rather mixed results, both de and yield being (g) substrate dependent. The authors finish the transformation by removing the sulfonim-idamide by reduction to leave a benzylic or allylic amine. 

Autoxidation of an impurity of meperidine (XII) leads to the aroma-tization product (XIII) (57) (Fig. 10). Some time ago, this was the major feature in an important criminal case, because this impurity, found in a drug manufactured illicitly, produced a severe parkinsonian syndrome in men. The tetrahydropyridine ring, not uncommon in pharmaceuticals, easily gives aromatization. In fact, the allylic methylene group adjacent to the nitrogen atom is activated and two dihydropyridine molecules formed by this oxidation may disproportionate to the finally aromatized product and to the starting material (57). 

The IV is defined as an average total number of double bonds per mole in a mixture of fatty materials. It is not a good descriptor for correlating physical and chemical properties with fatty acid composition in biodiesel. For example, the IV does not provide any information on structural factors such as number of allylic or bis-allylic methylene groups or location of double bond(s) within the hydrocarbon chain. Knothe (2002) recommended alternative indices termed allylic position equivalents (APE) and Ws-allylic position equivalent (BAPE) based on the total number of allylic and bis-allylic positions present in the fatty acid chains. 

Ziegler and coworkers 2 indicated that allylic methylene groups undergo bromine substitution more readily than allylic methyl groups. This has been shown 3 to be true, and the treatment of 2-heptene with N-bromosuccinimide gives rise to 4-bromo-2-heptene. 

Hydroxylation of the allylic methylene group in a- and 5,6-epoxides 56 and 57 was very effectively realized by a combination of selenium dioxide and pyridine N-oxide in dioxane [22 a]. Starting from 56 the Ip-hj-droxy isomer of 58 was obtained as a single product (Eq. 8) while, under the same conditions, the acetate 57 was converted to a 78 22 mixture of the la- and 1 5-hydroxy isomers 59a and 59b, respectively (Eq. 9). In this context it is interesting to note that a similar hydroxylation procedure with... 

In a series of papers, Minsker et al. (see, e.g., ref. 48) have claimed that all actual labile structure should be ketoallylic ( (C=0)-CH=CH-CHC1 ). The formation of this group is suggested to occur by oxidation of allylic methylene groups during the production and storage of PVC. As an alternative, Svetly et. al. (49-51) have suggested that this structure should exert its adverse effect by... 

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