Cyclo-pent

A basically new type of synthesis of dihydrooxazines was applied for the preparation of 177 and 179 (86JOC3248). Boron trifluoride catalyzed the intramolecular [4+2] cycloaddition of the A-acyliminium compounds derived from 176 and 178, resulting stereospecifically in the rrani-fused cyclo-pent[d][l,3]oxazines and partly saturated 3,1-benzoxazines 177 and 179, respectively. The steric orientation of the 4-methyl substituent of the product is controlled by the Z and geometry of the starting bisamides 176 and 178 (86JOC3248). 

The model values selected from cyclohexane-fused compounds may give somewhat overestimated contributions to the Z-out conformation in cyclo-pent[e][l,3]oxazines and -thiazines. 

CARBON YL(q s-CYCLO PENT ADIENYL)-(TETRAFLUOROBORATO)MOLYBDENUM AND TUNGSTEN COMPLEXES... 

Preparation of l-benzyl-2-[2-(2-hydroxyethyl)]-4-methoxy-l,6,7,8-tetrahydro-cyclo-pent[g]indole... 

Vinylcyclopropanols also readily undergo thermal rearrangement to cyclobutanones. l-(Cyclo-pent-l-enyl)- and l-(cyclohex-l-enyl)cyclopropanols 41 were converted quantitatively to the... 

Similarly, the reaction of l,2-diamino-3-chlorocyclopropenylium ion 24 with the cyclo-pent[e]azulenide ion afforded a mixture of l,2-diamino-3-(cyclopent[( ]a2ulen-l-yl)- and 1,2-diamino-3-(cyclopent[ ]azulen-3-yl)cyclopropenylium ions 25 and 26, which after deprotonation further reacted with the l,2-diamino-3-chlorocyclopropenylium ion to also give doubly cross-conjugated, tripolar mesomeric systems 28 and 29, consisting of two cyclopropenylium ions and one cyclopent[e]azulenide ion. ... 

Other basic zeolites are those prepared by Baba et al. [79], consisting of low-valent Yb or Eu species introduced into alkali ion-exchanged Y zeolites by impregnation with Yb or Eu metal dissolved in liquid ammonia then heating under vacuum at ca 470 K. These materials catalyze the Michael addition of cyclo-pent-2-enone and dimethyl malonate at 303 K, without solvent, yielding, after 20 h reaction, 81 % Michael adduct with 100% selectivity [80,81]. 

Patel RN, Banerjee A, Pendri YR, et al. Preparation of a chiral synthon for an HBV inhibitor enzymatic asymmetric hydrolysis of (la,2p,3a)-2-(benzyloxymethyl)cyclo-pent-4-ene-l,3-diol diacetate and enzymatic asymmetric acetylation of (la,2p,3a)-2-(benzyloxymethyl)cyclopent-4-ene-l,3-diol. Tetrahedron Asymmetry 17(2), 175, 2006. 

Photooxygenation of the ester alcohol 266 led to the allylic hydroperoxide 267 which could be converted into a series of 1,2,4-trioxane derivatives 268 (RVR = Adamantan, cyclo-Hex, cyclo-Pent, Me/Me and Et/FI) by BF3-catalyzed peroxyacetalization <2006LOC247> (Scbeme 79) the adamantane derivatives were characterized by X-ray diffraction and proved to be of moderate antimalarial activity. 

Cyclo- penta- diene Methanol (P(C4H,)jPdCy2 Methyl cyclo-pent-2-ene-carboxylate 73 [527]... 

Cycloalkenes undergo ring-opening polymerization in the presence of coordination initiators based on transition metals to yield polymers containing a double bond, for instance, cyclo-pentene yields polypentenamer [IUPAC poly(pent-l-ene-l,5-diyl)] [Amass, 1989 Cazalis et al., 2000, 2002a,b Claverie and Soula, 2003 Doherty et al., 1986 Ivin, 1984, 1987 Ivin and Mol, 1997 Ofstead, 1988 Schrock, 1990, 1994 Tmka and Gmbbs, 2001], The... 

Dicyclo-pentyl-3 (2-cyclo-pentylethyl) pent ane [D-Cd3 0 C22H40 80.4 126.6... 

Consider a telomer being formed from a cyclopentenyl polymer growing under the pairwise mechanism (Scheme 12.14) with growth being curtailed by cross-metathesis under two extreme conditions (i) with only pent-2-ene present (C4 C5 C6 = 0 100 0) and (ii) with a fully equilibrated mixture of acyclic monoalkenes (C4 C5 C6 = 1 2 1). Under condition (i), one would expect the formation of only hierarchical telomers (n = 1,2,3,4,5, etc.) of the type (C2)-[(cyc-C5) ]-(C3) as the pent-2-ene is split into a C2 and a C3 unit across the growing cyclo polyene. In contrast, under condition (ii), one would expect each hierarchical telomer to be formed in a 1 2 1 ratio of (C2)-[(cyc-C5)n]-(C2) (C2)-[(cyc-C5) ]-(C3) (C3)-[(cyc-Q)n]-(C3)> depending on whether there is cross-metathesis with C4, C5 or C6 (ratio = 1 2 1). The outcome will thus depend on how quickly the pent-2-ene is equilibrated by homo-metathesis to yield the C4, C5 and C6 mixture. Analysis of the rate of pent-2-ene homo-metathesis showed that it was not fast. Indeed, it proceeded at approximately the same rate as the telomerisation reaction. One would thus expect the telomer product early in the reaction to be essentially pure (C2)-[(cyc-C5) ]-(C3) species. Then, as C4 and C6 increase in concentration relative to C5, formation of the (C2)-[(cyc-C5) ]-(C2) and (C3)-[(cyc-C5) ]-(C3) telomers should increase proportionally. This was not found to be the case. 

B 15 2-R, 19th line from bottom H,H -Bis(phenylazo)-cyclo-2,3,5,6,7-pentamethylene-1,4-diamine, instead of. -2,3,5,7-pent am ethylene-. 

Fig. 3.5. Relationship between log (retention time) and boiling point for a range of hydrocarbons on squalane at 43°C. A, aliphatics (and benzene) B, alicyclics, 1-4 = C5-Cg n-alkanes 5 = 2-methyl-butane 6 = 2-methylpentane 7 = 2,3-dimethylbutane 8-12 = C4-C8 1-olefins 13,15,17 = trans-(but-2-ene, pent-2-ene and hept-2-ene) 14,16,18 = e/s-(but-2-ene, pent-2-ene and hept-2-ene) 19 = 2-methylbut-l-ene 20 = 2-methylpent-l-ene 21 = 4-methylpent-l-ene 22 = 2-methylbut-2-ene 23 = cyclopentane 24 = cyclohexane 25 = methylcyclopentane 26 = methylcyclohexane 27 = cyclo-pentene 28 = cyclohexene 29 = 4-methylcyclohexane 30 = 1,3-butadiene 31, 32 = trans- and cis-1,3-pentadiene 33 = diallyl 34, 35 = trans- and c s-2-methyl-l,3-pentadiene 36 = cyclopentadiene ...

The combination of diethylzinc and chloroiodomethane was employed in the synthesis of carbo-cyclic cyclopropyl nucleosides projected for biological evaluation. Attempts to cyclopropanate the intermediate a,j8-unsaturated ester, methyl (Z)-4,5-(isopropylidenedioxy)pent-2-enoate, gave a low yield (10%) of the desired cyclopropyl product. However, hydroxy-directed cyclo-propanation vide infra) of the reduced allyl alcohol 21 with diethylzinc/chloroiodomethane at 0°C afforded the cyclopropane derivative 22 in 54% yield. 

Under very carefully controlled conditions, irradiation of cyclopentadiene (1) gives bi-cyclo[2.1.0]pent-2-ene (2). The highly strained product is extremely sensitive to traces of acid or water, but its tetrahydrofuran solution can be stored indefinitely at — 78... 

At — 78 "C mcthylcnecyclopropane (1 7.3 g, 135 mmol) was added to a solution of (7/ -allyl)(f -cyclo-pentadienyl)palladium (500 mg, 2.25 mmol), i-PfjP (360 mg, 2.25 mmol) and methyl ( )-cinnamate (21.8 g, 135 mmol) in anhyd toluene (20 mL) in a 200-mL stainless steel autoclave. The autoclave was then heated to 120 C with shaking and kept at that temperature for 10 h. According to GC analysis, 5-methylene-spiro[2.4]hcptanc [yield 4.4 g (60.3yo)] and 12 [R = Ph yield 10 g (35.5%)] were obtained. On attempted purification by distillation (bath temp 100-160 C), 12(R = Ph) partly isomerized to give a 2 1 1 mixture of 12 (R = Ph), methyl 4-methyl-2-phenylcyclopent-3-cnccarboxylate and methyl 3-niethyl-5-phenylcyclo-pent-2-enecarboxylate bp 65-70°C/10 Torn... 

Cyclizations of pent-4-enyl radicals are very interesting, because neither the 4-exo trig nor the 5-endo trig cyclizations are considered favorable (Eq. 4). The 4-exo cyclizations are unfavorable because of the strain and rapid opening of the cyclo-butylmethyl radical to pent-4-enyl radical, whereas the 5-endo trig cyclization is disfavored based on Baldwin s rules of ring closures [18]. As in the case of 3-exo cyclizations, neither the 4-exo nor 5-endo radical cyclization reactions were reported in the literature prior to 1988. 

Mixture of (2-methyl-4-oxo-3-pent-2-enyl)cyclopent-2-enyl lR[l-a[S (Z)],3p]]-2,2-dimethyl-3-(2-methylprop-l-enyl) cyclo propanecarboxylate)... 

Isomerisation.—Mechanisms of isomerisation of pent-l-ene, hex-l-ene, and hept-l-ene have been discussed, with particular reference to the reduction behaviour of the respective catalysts. Thus there is an induction period for the ruthenium-trichloride-catalysed isomerisation of hex-l-ene since reduction of ruthenium trichloride to the active ruthenium(i) species is slow. There is no induction period for rhodium-trichloride-catalysed isomerisation since reduction to rhodium(i) is rapid. Isomerisation of cyclic alkenes, particularly of the cyclo-octadienes, has attracted some attention, " There has been discussion on whether the 1,4-isomer is an intermediate in the isomerisation of 1,3-cyclo-octadiene to the 1,5-isomer and vice versa the 1,4-isomer has now been detected in isomerisation of the 1,3-compound catalysed by PdCl2(benzonitrile)2 in benzene solution. Isomerisation... 

C15H24 l,7-dimethyl-7-(4-methyl-pent-3-enyl)-2,6-cyclo-norbornane 512-61-8 ... 

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