Chloromethylene Compounds

PRODUCT EMPIRICAL FORMULA MOL. WT. PHYSICAL CONSTANTS ASSAY (Method) ISOMER CONTENT (Prox.) 

Refractive index QZ0 C Specific gravity QZ0/4 C Surface tension QZS C Vapor pressure Q100 C Viscosity 

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Reaction of 55a with thionyl chloride gave the 3-chloromethylene compound (55b) (62%) and with isopropyl iodide the 3-isopropoxy-methylene derivative (55c) (57%). Hydroxylamine condenses with... 

An extension of the Erlenmeyer synthesis is the condensation of acylamino acids with triethyl orthoformate which leads to the ethoxymethylene derivatives (297). These can be hydrolyzed to the corresponding enols, which in turn can be converted into chloromethylene compounds, e.g. (298). The lability of the chlorine atom in this compound (see arrows) can be put to good account reaction with organometallic compounds or with benzene and its derivatives under Friedel-Crafts conditions yields unsaturated lactones (298 aryl or heteroaryl in place of Cl). The method is especially valuable in cases where the aldehyde is not readily available. 

Reaction of unsaturated 5(4//)-oxazolones with appropriate nucleophiles affords new unsaturated 5(4//)-oxazolone analogues used as intermediates to prepare a variety of interesting compounds. 4-(Chloromethylene)-5(4/i/)-oxazolones react with a variety of nucleophiles. For example, 4-(chloromethylene)-2-phenyl-5(4F/)-oxazolone 395 reacts with imidazole to afford 4-[(imidazol-l-yl)methyl-ene]-2-phenyl-5(4F/)-oxazolone 396. The authors found no evidence for the product derived from carbon-carbon bond formation, that is, 4-[(imidazol-4-yl)methylene]-2-phenyl-5(4//)-oxazolone (Scheme 7.126). 

Di Cesare and Gross175 introduced a procedure using phase-transfer catalysis to induce the action of dichlorocarbene on various protected sugars,176 and obtained the chloro derivative 162c from compound 161. Another, similar migration was observed,178 and confirmed,134,174 for the chlorination of methyl 2,3-anhydro-4,6-0-benzylidene-a-D-al-lopyranoside (166) with (chloromethylene)dimethyliminium chloride, which gave the rearranged chloro derivative 167. 

In contrast to guanidine-2-carbonitriles,395 isourea-3-carbonitriles (Ai-cyanocarbamimidates) and related compounds give good yields of chloro-l,3,5-triazines 11 in condensation reactions with (chloromethylene)iminium salts.397... 

Rao3 recently reported that aromatic aldehydes condense with hip-puric acid in polyphosphoric acid (PPA) to give the generally inaccessible lower-melting geometric isomers of 4-aryl-methylene-2-phenyl-2-oxazolin-5-ones, e.g., 1, Eq. (1). The Erlenmeyer method and its minor variations, such as use of 4-chloromethylene or 4-ethoxy-methylene azlactones, always afford the geometric isomer,1,2 e.g., 2. Compound 2 is quantitatively isomerized to 1 in PPA [Eq. (2)]. The... 

Mark and Rechnitz [3] systematized a vast amount of experimental material that can be used directly in KGCM. Some data are presented here that show the wide differences in organic compounds with regard to their kinetic characteristics. Table 2.1 [14] gives the relative rates of reaction of olefins with perbenzoic acid and Table 2.2 summarizes the rates of the etherification reaction of carboxylic acids with diphenyldiazomethane [15]. The tabulated data are indicative of large differences in organic compounds as far as their reactivity is concerned. The rates of reaction of some isomers differ so widely that one can, for example, analyse secondary and tertiary alkyl bromides in the presence of primary alkyl bromides in a reaction with silver nitrate [16]. It is possible to differentiate between CIS and trans isomers of 1,3-dienes by their reaction with dienophils (e.g., chloromethylene anhydride) because the cis isomer reacts much more slowly than the trans isomer [17]. 

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