2,2 -methylene bis

A single example is known for a palladium(0)-catalyzed cotrimerization reaction involving two molecules of an alkene and a methylenecyclopropane molecule, leading to the formation of a seven-membered-ring product.The reaction is limited to unsubstituted allene and, along with the cyclotrimer, l,3,5-tris(methylene)cycloheptane (3), 1,3-bis(methylene)cyclopen-tane (2), the product of a [3 + 2] cycloaddition, is also obtained. The product ratio 2/3 is markedly dependent on the catalyst composition. Additionally, the allene trimer, 1,2,4-tris(methyl-ene)cyclohexane (4), and the methylenecyclopropane homodimer, 5-methylenespiro[2.4]hep-tane (5), are formed. 

Copovithane [1,3 bis (methylaminocarboxy)-2 methylene propane carbamate and JV-vinylpyrrolidone copolymer) (Mw = 5 800) Active against sarcoma 180, P388 leukemia, and carcinoma F077I in mice, and Walker 1098 in rats. Inactive in vitro, and is suspected to act through stimulation of host immune system 67... 

Exocyclic unsaturation can stabilize small ring heterocycles. In three-membered rings it is difficult to separate the contributions from increased angle strain and from electronic interactions between the unsaturation and the heteroatom. In four-membered rings such separation has been done (74PMH(6)199, p. 235). The CRSEs change "from oxetane (106 kJ mol-1) by -11 kJ mol-1 to oxelan-2-one (95 kJ mol-1) (corrected for electronic effects) and 4-methyleneoxetan-2-one (95 kJ mol" ). In contrast, an increase of 10 kJ mol 1 over the value for cyclobutane (111 kJ mol-1) is observed on going to both methylenecyclobutane and l,3-bis(methylene)cyclobutane. 

Homologation of 1,3-dienes.1 The reagent is particularly useful for cyclohomologation of 1,3-dienes. Thus the adduct a of a Diels-Alder reaction of 1 with 1,2-bis(methylene)cyclohexane undergoes Ramberg-Backlund rearrangement to the tri-ene 2. Repetition of the sequence provides the tetraene 3. The sequence is applicable to cyclopentadiene, furan, and 2,3-dimethyl-l,3-butadiene. 

A Comparison of Selected Structural Data for (i-cii-2,3-DiMETHYLBUTADiENE)- and [1,2-Bis(methylene)cyclohexane]zirconocene (5g, So) and -hafnocene (5n, 5p)... 

A simple route to 2,3-bis(methylene)butanedioic esters involves carbonylation of l,4-bis(ethoxycarbonyloxy)-2-butyne. 2-Pyrimidyldiphenylphosphine is a suitable ligand for carbonylation of 1 -alkyne to give 2-substituted acrylic esters. ... 

X = Cl, Br) were treated with potassium tert-butoxide in tetrahydrofuran to give 80% and 40% yield, respectively, of 7,7-dichloro- and 7,7-dibromo-2,3-bis(methylene)bicyclo-[4.1.0]heptane (19, X = Cl, Br). Elimination of the corresponding bis(mesylates) (see Section 5.2.2.3.) gave only low yields of bis(methylene) products. 

A double mesylate elimination using potassium /ert-butoxide in tetrahydrofuran was attempted as a means of preparing 7,7-dichloro-2,3-bis(methylene)bicyclo[4.1.0]heptane (14, X = Cl) and its 7,7-dibromo analog from the corresponding diols. However, only low yields of the dienes... 

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. 

An example in which an adjacent cyclopropyl moiety participates in the rearrangement is the vapor-phase pyrolysis of methylenespiropentane (21). When heated for 20 hours at 300 °C 21 yielded 1,2-bis(methylene)cyclobutane (22, 15.8%) and l,3-bis(methylene)cyclobutane (23, 19.8%), along with 60.6% of unreacted starting material. 

Theimolysis of tricyclo[3.2.1.0 ]octane (1) in diphenyl ether produced only polymer, but in the gas phase at 318°C, l,3-bis(methylene)cyclohexane was formed. " The highly strained bridgehead to bridgehead bond in [1.2.3]propellane 1 was readily cleaved by several different reagents to give molecules 2 containing seven-membered rings. 

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