Ethylidene compounds

The two possible homologues, with either one or two methyl groups on the methylene carbon of the methylenedioxy group of MDA, are also known. The ethylidene compound (the acetaldehyde addition to the catechol group) has been encoded as EDA, and the acetone (isopropylidine addition to the catechol group) is... 

The demonstration166 that the side-chains of 24-methylenecycloartanol (96), 24-methylenelophenol, and campesterol incorporated two deuterium atoms, whilst those of 24-ethylidenecycloartanol, stigmasterol, and sitosterol contained a maximum of four deuterium atoms when biosynthesized by cultures of barley embryo in the presence of [Me-2H3]methionine, provides further evidence for the intermediacy of 24-methylene- and 24-ethylidene-compounds in the biosynthesis of C28 and C29 phytosterols. The barley system was also able to convert labelled 24-ethylidenelophenol into radioactive sitosterol efficiently. These results, and those obtained from feeding experiments with [2-14C,(4R)-4-3Hi]MVA, are consistent with a pathway (Scheme 9) to stigmasterol (97) involving isomerization of (98) to a... 

Ethylene and Ethylidene Compounds.—The fact that the symmetrical di-chlor ethane is readily prepared from ethylene, has given to it the name of ethylene chloride. To distinguish the two isomers by name the other, the unsymmetrical di-chlor ethane, has been called ethylidene chloride. In connection with our discussion of the constitution of the ethene series of unsaturated hydrocarbons (p. 154), we have used the constitution of ethylene chloride as proving the constitution of ethylene or ethene, as H2C = CH2. Isomerism of the character shown in these two di-chlor ethanes, as above explained, is found in all classes of di-substitution products of ethane, so that we may express the compounds by general formulas as follows ... 

Higher temperatures are said to facilitate the formation of the ethylidene compound. Similar yields have been obtained, however, when the temperature was maintained at 50-55° during the entire reaction period. 

From this E-ethylidene compound, the alkaloid geissoschizine was synthesized in a similar way as in the synthesis of hirsuteine, beside the conversion of the configuration at the 3-position which was done first by dehydrogenation with cupric acetate and oxygen and the subsequent reduction with sodium borohydride. The products were a 1 1 mixture of 3oC- and 3p -derivatives, which was then formylated as before to furnish total synthesis of geissoschizine. 

A number of phytosterols contain a two-carbon side chain (ethyl or ethylidene) attached to C-24, the atom which is methylated in the formation of ergosterol. The scheme of Castle et al., reproduced partially in Fig. 2, was originally proposed to account for the formation of such compounds. It was postulated that the 24-methylene compound (structure IV) might be further methylated to yield the 24-ethyl or ethylidene compounds. Evidence in favor of such double methylations has been supplied by the findings that (1) the label from [methyl- C] methionine is incorporated equally into both carbon atoms C-28 and C-29 (Castle et al., 1963 Bader et al., 1964 Villanueva et al., 1964), and (2) 24-ethyli-dene compounds may be converted to the 24-ethyl compounds by whole Pinus pinea seed (van Aller et al., 1969). That the details of the reactions may differ is indicated by deuterium labeling patterns. In some cases, only four hydrogen atoms derived from methionine are incorporated... 

The acetal diastereomers were separated as their acetates by column chromatography. It was noted that 90% trifluoroacetic acid completely hydrolyzed the benzylidene derivatives in 2h at room temperature, whereas the ethylidene compounds were unaffected under these conditions the latter required boiling with aqueous acetic acid for 6h. The two anomers of methyl 4. 6- -benzylldene-... 

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). 

Acetyl chlotide is reduced by vatious organometaUic compounds, eg, LiAlH (18). / fZ-Butyl alcohol lessens the activity of LiAlH to form lithium tti-/-butoxyalumium hydtide [17476-04-9] C22H2gA102Li, which can convert acetyl chlotide to acetaldehyde [75-07-0] (19). Triphenyl tin hydtide also reduces acetyl chlotide (20). Acetyl chlotide in the presence of Pt(II) or Rh(I) complexes, can cleave tetrahydrofuran [109-99-9] C HgO, to form chlorobutyl acetate [13398-04-4] in about 72% yield (21). Although catalytic hydrogenation of acetyl chlotide in the Rosenmund reaction is not very satisfactory, it is catalyticaHy possible to reduce acetic anhydride to ethylidene diacetate [542-10-9] in the presence of acetyl chlotide over palladium complexes (22). Rhodium trichloride, methyl iodide, and ttiphenylphosphine combine into a complex that is active in reducing acetyl chlotide (23). 

The stereochemistry of the product resulting from the reaction of a 17-keto steroid with ethylidenetriphenylphosphorane is different from that of the 17-ethylidene steroids obtained by dehydration of 17a-ethyl-17/ -hydroxy compounds, Wolff-Kishner reduction of A -20-keto steroids or by sodium-alcohol or sodium-ammonia " reductions of 17-ethynyl carbinols. These latter products have generally been assumed to possess the trans configuration (C-21 methyl away from the bulk of the ring system) because of anticipated greater stability. The cis configuration for... 

TABLE 2 Effect of Injection Molding Temperature on 3,9-Bis-(ethylidene-2,4,8,10-tetraoxaspiro[5,5]undecane), (75 25) 1,6-Hexanediol / trans - Cyclohexanedimethanol Polymer Compounded with 3 wt% Phthalic Anhydride and 7.5 wt% Cyclobenzaprine Hydrochloride (CBP)... 

Stearic acid (5 wt%) was compounded with a linear polymer prepared from 3,9-bis(ethylidene-2,4,8,10-tetraoxaspiro[5,5]undecane) and a 30 70 mole ratio of 1,6-hexanediol and trans-cyclohexanedi-methanol by thermal, solvent, or powder methods (Table 4). The thermal method (flux mixer and roller mill) resulted in good stearic... 

The violent polymerisation of acryl acid caused a violent fire on a boat that was transporting it. The investigation showed that this acid contained ethylidene norbornene, which is a very oxidisable compound that forms a peroxide in air, which caused the acid polymerisation. 

L-tryptophan is a naturally-produced, natural amino acid used as a dietary supplement. Samples from one manufacturer were found to be contaminated by trace amounts of another naturally occurring compound — l,l -ethylidene bis-[i.-tryptophan]. The latter compound appears to have been responsible for causing a number of deaths and additional cases of chronic eosinophilia-myalgia,111 some of which might have been prevented had there... 

The thermal reaction of dipropynylsilanes with AII3B also involves 1,1- and 1,2-allylboration of the triple bond (or vice versa) (Scheme 50). l-Sila-3-bora-2-ethylidene-4-cyclopentene derivatives 119 are formed quantitatively at room temperature. They undergo an intramolecular 1,2-allylboration on heating for 3h to give the corresponding bicyclic compounds 120 quantitatively <2002JOM(649)232>. 

The lower trace in Figure 1 shows the results of heating the tunnel junctions (complete with a lead top electrode) in a high pressure cell with hydrogen. It is seen that the CO reacts with the hydrogen to produce hydrocarbons on the rhodium particles. Studies with isotopes and comparison of mode positions with model compounds identify the dominant hydrocarbon as an ethylidene species (12). The importance of this observation is obviously not that CO and hydrogen react on rhodium to produce hydrocarbons, but that they will do so in a tunneling junction in a way so that the reaction can be observed. The hydrocarbon is seen as it forms from the chemisorbed monolayer of CO (verified by isotopes). As... 

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