Dienyl

Nb-alkyls and aryls, e.g. MeNbCL and NbMe, Me2pCH2CH2pMe2) are known although relatively unstable. Cyclopenta-dienyl derivatives (h — C5Hs)2NbX3, (h -CjH5)Nb(CO)4 are relatively stable as is [Nb(CO)6] (NbClj + Na in diglyme + CO (pressure)). Tantalum compounds are very similar. 

Allylic amines are coupled to halides giving either allylic amines or enamines depending on the reaction condition. Reaction of steroidal dienyl triflate with Boc-diprotected allylamine affords allylamine. Use of AcOK as a base is crucial for the clean coupling[102]. The tert-allylic amine 123 reacts with an aryl halide to give the enamine 125 in DMF and allylic amine 124 in nonpolar solvents[103]. 

Write the most stable resonance structure for the cyclohexa dienyl anion formed by reaction of methoxide ion with o fluoronitrobenzene J... 

Univalent radicals have the endings -enyl, -ynyl, -dienyl, -diynyl, etc. When necessary, the positions of the double and triple bonds are indicated by locants, with the carbon atom with the free valence numbered as 1. Examples ... 

The addition proceeds in three discrete steps and the intermediates can be isolated. Simple alkenes are less reactive than alkynes and do not undergo the addition to aHylic boranes, but electron-rich alkyl vinyl ethers react at moderate temperatures to give 1,4-dienes or dienyl alcohols (440). 

Hexafluorophosphate and tetrafluoroborate dienyl salts react with many nucleophiles. The tetrafluoroborate salts are to be preferred, being more soluble in organic solvents than the hexafluorophosphates. 

Iron pentacarbonyl and l-methoxy-l,4-cyclohexadiene react as shown by Birch and oo-workera, but in dibutyl ether this solvent has been found superior. The tricarbonyl(methoxy-l,3-cyclohexadiene)iron isomers undergo hydride abstraction with triphenylmethyl tetrafluoro-borate to form the dienyl salt mixture of which the 1-methoxy isomer is hydrolyzed by water to the cyclohexadienone complex. The 2-methoxy isomer can be recovered by precipitation as the hexafluoro-phosphate salt. By this method the 3-methyl-substituted dienone complex has also been prepared from l-methoxy-3-methylbenzene. The use of the conjugated 1-methoxy-1,3-cyclohexadiene in Part B led to no increase in yield or rate and resulted chiefly in another product of higher molecular weight. An alternative procedure for the dienone is to react tricarbonyl(l,4-dimethoxycyclohexadiene)iron with sulfuric acid. ... 

Since the vinyl-C//proton at (<5//= 6.33 shows no additional V////couplings apart from the doublet of doublets splitting (cis and trans coupling), the side-chain is a 1-isoprenyl chain E and not a 1-methylbuta-l,3-dienyl residue F. 

Elemental and inorganic compounds Manganese cyclopenta-dienyl tricarbonyl as Mn Manganese methyl-pentadienyl tricarbonyl Manganese tetroxide Man-made mineral fibre Marble, see Calcium carbonate Mercaptoacetic acid, see Thioglycolic acid Mequinol (INN)... 

A variety of conjugated dienones are reduced by lithium-ammonia, presumably via dienyl carbanions analogous to the allyl carbanions encountered in enone reductions. Cross-conjugated l,4-dien-3-ones afford 4-en-3-ones as the major reduction products, indicating that the cyclohexadienyl carbanion (55) protonates largely at C-1. Some protonation at C-5 does occur as shown by examination of the NMR spectrum of the crude reduction product derived from the 17-ethylene ketal of androsta-l,4-diene-3,17-dione. The 17-ethylene ketal of androst-4-ene-3,17-dione is formed in 75%... 

Reduction of linearly conjugated 4,6-dien-3-ones with lithium-ammonia yields either 5-en-3-ones or 4-en-3-ones depending upon the work-up procedure. Protonation of the dienyl carbanion intermediate (58) occurs at C-7 to give ultimately the enolate ion (59) kinetic protonation of (59) occurs largely at C-4 to give the 5-en-3-one (60). ... 

Protonation of the dienyl carbanion formed by reduction of a linear dienone may occur at a carbanion center either p or S to the carbonyl group as is implied by the resonance structures shown below ... 

Most dienones that have been reduced have structures such that they cannot give epimeric products. However, reduction of 17 -hydroxy-7,17a-dimethyl-androsta-4,6-dien-3-one (63) affords 17 -hydroxy-7j9,17a-dimethylandrost-4-en-3-one (64), the thermodynamically most stable product, albeit in only 16% yield. The remainder of the reduction product was not identified. Presumably the same stereoelectronic factors that control protonation of the / -carbon of the allyl carbanion formed from an enone control the stereochemistry of the protonation of the (5-carbon of the dienyl carbanion formed from a linear dienone. The formation of the 7 -methyl compound from compound (63) would be expected on this basis. 

Manganese, tricarbonyl methylcyclopenta dienyl, 86 Manufacturers Association of Israel - MAI Manufacturers Chemicals L.P, 237, 249 MANZATE , maneb, 86 Maranda Mining Company (Pty) Ltd., 199 Marathon Ashland Petroleum LLC, 237 Marble, 86... 

Under sonication conditions, the reaction of perfluoroalkyl bromides or iodides with zinc can be used to effect a variety of functionalization reactions [39, 40, 41, 42] (equation 30) Interestingly, the ultrasound promoted asymmetric induction with the perfluoroalkyl group on the asymmetric carbon was achieved by the reaction of perfluoroalkyl halides with optically active enamines in the presence of zinc powder and a catalytic amount of dichlorobisftc-cyclopenta-dienyl)titanium [42] (equation 31)... 

Attempts to prepare the mono(cyclopenta-dienyl) derivatives are sometimes frustrated by a Schlenk-type equilibrium (see p. 132), but judicious choice of ligands, solvent etc. occasionally permits the isolation of such compounds, e.g. the centrosymmetric halogen-bridged dimer (t - -C5Me5)Ca(/i-l)(lhf)2 2] which cry.stallizes from toluene solution. The complex is isostruc-tural with the dimeric organosamarium(ll) analogue. - ... 

Conjugated diene (e.g. butadiene), cyclobutadiene derivatives Dienyl (e.g. cyclopentadienyl derivatives, cycloheptadienyl derivatives)... 

Azaferrocene reacts with aromatic hydrocarbons in the presence of aluminium chloride, giving rise to the cationic complexes of the type (Ti -arene)(Ti -cyclopenta-dienyl)iron(l+) isolated as BF4 salts [87JOM(333)71]. The complex 28 is obtained by reaction of the sulfane compound [Cp(SMc2)3Fe]BF4 with pentamethyl-pyrrole [88AG(E)579 88AG(E)1468 90ICA(170)155]. The metallic site in this center reveals expressed Lewis acidity (89CB1891). 

Diacetylene reacts with ethyleneglycol in the presence of alkalis at 75-140°C to form a mixture of 2-(prop-2-ynyl)-l,3-dioxolane (36), 2-(propa-l,2-dienyl)-l,3-dioxolane (37), and 2-(prop-l-ynyl)-l,3-dioxolane (38) (1-5 h, yield 66%), the ratio of which depends on the experimental conditions (74ZOR953). 

I We could remove a hydrogen ion rvith no electrons (H+). leaving a cyclopenta-dienyl anion. 

Active Figure 15.5 An orbital view of the aromatic cyclopenta-dienyl anion, showing the cyclic conjugation and six tt electrons in five p orbitals. The electrostatic potential map further indicates that the ion is symmetrical and that all five carbons are electron-rich (red). Sign in at www.thomsonedu.com to see a simulation based on this figure and to take a short quiz. 

Pyrrolo[l,2-a]azepin-9-one (12), which in acid solution exists as the cation 13, is prepared by thermal cyclization of ( , )-4-(dimethylaniino)buta-l,3-dienyl pyrrol-2-yl ketone (ll)7. 

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