L-methylene-3-

Subsequent reaction of (7) with the iodomethylzinc iodide reagent gives l/ ,2/l-methylene-3/l-hydroxy-A5-steroids which are readily transformed to the important 3-keto-A4 analogs.219,220... 

In all cases, linear polymers were obtained with chains that consisted predominantly of l-methylene-3-cyclopentyl or l-methylene-3-cyclohexyl units, respectively, and were characterised by a chain planar zigzag conformation [446, 495, 496],... 

Cyclopolymerisation may also concern the formation of polymers containing bicyclic repeating units. This is the case of the cyclopolymerisation of 3-vinyl-1,5-hexadiene, which yields polymers with l-methylene-3-(2,5-methanocyclo-hexyl) units [494] ... 

In the photocyclization of 2-aroyl-l-methylene-3,4-dihydroisoquino-lines, a complete expulsion of oxygen from the solvent is required in order to avoid the formation of the dehydrolactam (31,32,44). Under unrestricted conditions using commercially available solvent that is not completely degassed, the dehydrolactams (9) are predominantly formed in addition to a small amount of the nonoxidative product (21-24) (Scheme 14). 

Total synthesis of protoberberine alkaloids via the route involving enamide photocyclization consists of nonoxidative photocyclization of the 2-aroyl-l-methylene-3,4-dihydroisoquinolines and the subsequent metal-hydride reduction of the photocyclized lactams. This simple combination of reactions for alkaloid synthesis provides one of the most convenient synthetic routes to this group of popular alkaloids. 

The photolysis of 4-vinylcyclohexene in pentane at 185nm gave four products, isomers of the starting material, in 25% total isolated yield l-methylene-3-vinylcyclopentane (8) and three-membered rings exo- and endo-2- r y - and exo-3-vinylbicyclo[3.1.0]hexanes (9, 10 and 11, respectively) in the ratio 8/9/10/11 27.6 11.6 37.8 23. ... 

Cumulenes such as allenes also react with MCP in the presence of palladium(O) catalysts. With allene as substrate, 5-methylenespiro[2.4]heptane (23% yield) can be obtained along with the [3-h2] cycloadduct, l,3-bis(methylene)cyclopentane, in 40% yield. A third product of the reaction, however, is a [3-I-2-I-2] cycloadduct (see Section 2.2.2.3.3.). When the less reactive 1,1-dimethylallene (12) is employed, no [3 -I-2-L2] adduct is formed. Instead, the [3-f 2] adduct, l-methylene-3-(l-methylethylidene)cyclopentane (13), can be obtained in 11-25% yield, depending on the specific catalyst.The major product is 5-methylenespiro[2.4]heptane (7), while 2,5-dimethyl-3-methylenehexa-l,5-diene (14) and dimethylallene trimers are additionally formed. 

VpF and /ff couplings have been determined by Przyborowski et al from an analysis of the low-temperature spectrum of T-isopropyloamino-T-phenyl-l-methylene-3,3,4,4-tetrafluorocyclopentan-2,5-dione, a member of a newly synthesised series of fluorinated P-enaminoketones. Two-bond F-F... 

Seven-membered Rings.—Whereas pyrolyses of 5-acetoxymethylcycloheptene at 350 °C in a flow system gave mixtures of bi- and tri-cyclic products, pyrolysis in a sealed tube gave a mixture of 5-methylenecycloheptene and l-methylene-3-vinyl-cyclopentane. " Reactions of cyclohepta-2,6-dienone with substituted hydrazines, hydroxylamines, and carbohydrazines, gave the adducts (217). ... 

The synthesis of bis N-heterocyclic chelate ligand (bNHC) namely l,l -methylene-3,3 -di-2,6-diisopropylphenylimidazole-2,2 -diyli-dene is carried out by modification of the literature procedures (4,5). 

Benzofulvene derivatives are isomers of corresponding naphthalene derivatives that have been relatively less studied than their monocyclic and tricyclic counterparts. A particular mention can be made for 7-methyl-l-methylene-3-phenylindene (BF2, Fig. 2), a benzofulvene derivative described by Londergan and coworkers, that was reported to polymerize under free radical catalysis to afford a vinyl polymer containing pendant aromatic chromophores [15]. 

---