Olefins terminal

2- isopropyl-4-pentenamide (AIA) and 5-allyl-substituted barbiturates such as secobarbital  

The only structural requirement for prosthetic heme alkylation by olefins is a monosubstituted double bond. Accordingly, ethylene, but not ethane, is able to destroy the P450 heme while 

Spectroscopic methods have unambiguously established the structures of A -alkylated porphyrins isolated from the livers of rats treated with diverse olefins, including ethylene, propene, octene, fluroxene, 2,2-diethyl-4-pentenamide, 2-isopropyl- 

The regiochemistry and stereochemistry of heme alkylation by ran5-[l- FI]-l-octene has established that the olefin stereochemistry is preserved 

Several mechanisms can be envisaged for heme alkylation that are consistent with the experimental data, none of which involves a concerted transfer of the oxygen to the rr-bond. Subsequent to possible formation of a charge transfer complex between the ferryl species and the olefin -ir-bond, addition of the oxygen to the Tr-bond could give a 

The rate of hydroboration of 1-alkene (RCH=CH2) is nearly independent of the length of the straight chain. However, branching in the R group, decreases the rate of hydroboration  

Branching at position more remote from the double bond, such as at position C-4, has little or no effect on the rate. 

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TrialkyIboranes (p. 9), which can be synthesized from olefins and diborane, undergo alkyl coupling on oxidation with alkaline silver nitrate via short-lived silver organyls. Two out of three alkyl substituents are coupled in this reaction. Terminal olefins may be coupled by this reaction sequence in 40 - 80% yield. With non-terminal olefins yields drop to 30 - 50% (H.C. Brown, 1972C, 1975). 

A typical example of a nonpolymeric chain-propagating radical reaction is the anti-Markovnikov addition of hydrogen sulfide to a terminal olefin. The mechanism involves alternating abstraction and addition reactions in the propagating steps ... 

Linear terminal olefins are the most reactive in conventional cobalt hydroformylation. Linear internal olefins react at less than one-third that rate. A single methyl branch at the olefinic carbon of a terminal olefin reduces its reaction rate by a factor of 10 (2). For rhodium hydroformylation, linear a-olefins are again the most reactive. For example, 1-butene is about 20—40 times as reactive as the 2-butenes (3) and about 100 times as reactive as isobutylene. 

Several side reactions or post-cuting reactions are possible. Disproportionation reactions involving terminal hydride groups have been reported (169). Excess SiH may undergo hydrolysis and further reaction between silanols can occur (170—172). Isomerization of a terminal olefin to a less reactive internal olefin has been noted (169). Viaylsilane/hydride interchange reactions have been observed (165). 

Straight-chain terminal olefins are more reactive than straight-chain internal olefins, which are more reactive than branched-chain olefins (133). 

Synthesis of terminal olefine from ketones or esters via a Ti methylene transfer reagent. 

A GENERAL SYNTHETIC KTHQO FOR THE PREPARATION OF ICTHYL KETONES FROM TERMINAL OLEFINS 2-DECANONE... 

Hexafluoroacetone azine reacts with 2 equivalents of terminal olefins [194] and acetylenes [182] to give 1,5-diazabicyclo[3.3.0]octanes and 1,5-diazahicy-clo[3 3 0]octa-2,6-dienes, respectively (equation 44). 

Due to the radical nature of the Hofmann-Lbffler-Freytag reaction, a deviation was observed when there was a pendant terminal olefin on the substrate. When the aminyl radical from N-chloroamine 31 had a choice between addition to the double bond... 

In 1974, Hegedus and coworkers reported the pa]ladium(II)-promoted addition of secondary amines to a-olefins by analogy to the Wacker oxidation of terminal olefins and the platinum(II) promoted variant described earlier. This transformation provided an early example of (formally) alkene hydroamination and a remarkably direct route to tertiary amines without the usual problems associated with the use of alkyl halide electrophiles. 

Condensation of allyl isocyanate with succinimide affords the cyclic diacylurea 39. Acid hydrolysis leads to ring opening of the succinimide (40). Oxymercuration of the terminal olefin bond with mercuric acetate in methanol solution affords the diuretic meralluride (41). ... 

Some generalizations that pertain are (1) Terminal olefins are more rapidly reduced than internal olefins (2) conjugated olefins are not reduced at 1 atmosphere (3) ethylene is not hydrogenated. Rates of reduction compare favorably with those obtained by heterogeneous catalysts such as Raney nickel or platinim oxide. In fact, the hydrogenation of some olefins may be so rapid that the temperature of the solution (benzene) is raised to the boiling point. 

The secondary free radical can crack on either side of the carbon carrying the unpaired electron according to the beta scission rule, and a terminal olefin is produced. 

Linear low-density polyethylene (LLDPE) is produced in the gas phase under low pressure. Catalysts used are either Ziegler type or new generation metallocenes. The Union Carbide process used to produce HDPE could be used to produce the two polymer grades. Terminal olefins (C4-C6) are the usual comonomers to effect branching. 

The third and very valuable discovery that the new phthalazine (PHAL) and pyrimidine (PYR) ligand classes (32-35, Figure 2) out-perform the monomeric ligands under identical conditions emerged from a heuristic screening process. The PHAL class in particular has become the first choice for most olefin classes. The PYR class is usually superior for terminal olefins, while the IND class is ideally suited for cA-disubstituted olefins. These ligands are commercially available or can be made easily from relatively inexpensive starting materials. 

Molybdenum hexacarbonyl [Mo(CO)6] has been vised in combination with TBHP for the epoxidation of terminal olefins [44]. Good yields and selectivity for the epoxide products were obtained when reactions were performed under anhydrous conditions in hydrocarbon solvents such as benzene. The inexpensive and considerably less toxic Mo02(acac)2 is a robust alternative to Mo(CO)6 [2]. A number of different substrates ranging from simple ot-olefms to more complex terpenes have been oxidized with very low catalytic loadings of this particular molybdenum complex (Scheme 6.2). The epoxidations were carried out with use of dry TBHP (-70%) in toluene. 

Table 6.5 Epoxidation of terminal olefins by the Noyori system. 1.5 equiv. H202 (30% aq)...

A major improvement regarding epoxidation of terminal olefins was achieved upon exchanging pyridine for its less basic analogue 3-cyanopyridine (p Krl pyridine = 5.4 pKa 3-cyanopyridine = 1.9) [105]. This improvement turned out to be general for a number of different terminal olefins, irrespective of the existence of steric hindrance at the a-position of the olefin or the presence of other functional groups in the substrate (Scheme 6.13 and Table 6.9). 

High-valent ruthenium oxides (e. g., Ru04) are powerful oxidants and react readily with olefins, mostly resulting in cleavage of the double bond [132]. If reactions are performed with very short reaction times (0.5 min.) at 0 °C it is possible to control the reactivity better and thereby to obtain ds-diols. On the other hand, the use of less reactive, low-valent ruthenium complexes in combination with various terminal oxidants for the preparation of epoxides from simple olefins has been described [133]. In the more successful earlier cases, ruthenium porphyrins were used as catalysts, especially in combination with N-oxides as terminal oxidants [134, 135, 136]. Two examples are shown in Scheme 6.20, terminal olefins being oxidized in the presence of catalytic amounts of Ru-porphyrins 25 and 26 with the sterically hindered 2,6-dichloropyridine N-oxide (2,6-DCPNO) as oxidant. The use... 

In our work with aminolysis of vinylepoxides (see Section 9.2.1.1), the substrates were routinely synthesized by SAE followed by Swern/Wittig reactions (Table 9.3, Entries 1-4) [48, 49]. This procedure is well suited for terminal olefins, but dis-ubstituted olefins can seldom be obtained with useful (E Z) selectivities. Nakata recently synthesized some advanced intermediates towards natural products in this manner (Entries 5, 6) [50, 51]. 

Asymmetric epoxidation of terminal olefins has remained problematic, despite the general success of the novel dioxirane-based catalysts. The enantiomeric excesses in these reactions do not usually exceed 85% (see Section 9.1.1.1). As recrystallization of epoxides can be complicated, enantiopure terminal epoxides are difficult to obtain. 

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