Allyl analogues

MeSSMe and inhibited to isomerise by a significantly larger isomerization barrier of 340 kj mol Thus, both H2S=S and Me2S=S are predicted to be kinetically stable toward unimolecular isomerization and should be experimentally observable in the gas phase or after matrix isolation. HF/b-SlG calculations indicate that the allyl analogue has a similar R2S=S/RSSR energy difference but a substantially lower activation barrier (110 kJ mol ) for rearrangement [25]. 

The carbamates 327 (R R2 Pr or Bu) react with t-butylthiol, malonic acid and ethoxyethylene under irradiation to yield the (ethoxyethyl)amines 333 via the radical cations 332. The A-allyl analogues 334 (R = Pr or PhCH2) cyclize to pyrrolidines 335382. 

It is N-allyl analogue of oxymorphone, have a high affinity for mu receptor and lower affinity at delta and kappa sites. It selectively antagonizes the respiratory depression produced by opioids. After intravenous administration, it antagonizes all actions of morphine. It also blocks the actions of endogenous opioid peptides. 

Naltrexone and nalmefene are structurally related to naloxone. Naltrexone is the /V-cyclopropy I methyl analogue of oxymorphone while nalmefene is the /V-allyl analogue. They have similar pharmacological properties to naloxone but with longer durations of action, with elimination half-lives in excess of 8 hours. They also have significant oral availability. They are used mainly in the management of addicts. 

However, when a mixture of both crotyl regioisomers 60 and 61 were obtained and separated, unambiguous assignment of C-9 to an a orientation could be ascertained from NMR coupling constants (Eq. 17). After this comparison, it was clear C-9a allyl analogue 59 had been produced earlier. However, 59 underwent kinetic enolization with LDA at low temperature and subsequent acid quench afforded desired C-9P allyl analogue 57. 

Simple homologous olefins at C-9, such as the allyl analogue 57 were planned to examine the effect of donors. Allyl analogue 57 was surprisingly only 30-70% as potent as artemisinin. Compared to the propyl or aryl analogues, this was an unexpected result. 

The cycloarsines (PhAsj and (MeAs)j also behave as sources of the isolobal arsenic analogue of the allyl ligand, i.e. RAsAsAsR, on reaction with [Cp M 0)2] 2 (for M = Mo or W) to give products with the stoichiometry Cp M(CO)2 (RAsAsAsR) . Each arsenic atom is bonded to the transition metal and the As—As distances are equal (2.361 A), representing a bond order of 1.5 as expected for an allylic analogue. 

Keywords Silicon-Phosphoms Compounds / Silicon-Arsenic Compounds / Silylidene-phosphanes and -arsanes / Silaheterocycles / Allyl Analogues... 

The use of propargyltrimethylsilane as ir-nucleophile may lead to cyclic products. Thus, reaction of ethoxycarbamate (136) in the presence of SnCU gives oxazinone (137) as the sole product in 56% yield (equation 102). However, when EtAlCb is used as Lewis acid, a 75 25 mixture of (137) and allene (138) is obtained in 63% total yield. Interesting further details are that 1-pentyne does not react with (136) under similar conditions and that allyltrimethylsilane produces the allyl analogue of (138) in almost quantitative yield. It remains unclear whether (138) arises via the intermediacy of a cycloadduct or is formed directly from (136) without involvement of the carbonyl function. 

Figure 9 Cleavage of 3, 4 -anhydroadenosylcobalamin at the active site of DDH. Cleavage of the Co-C bond leads to cob(ll)alamin and the allylic analogue of the 5 -deoxyadenosyl radical. The resulting triplet radical is observed and characterized by EPR spectroscopy. ...

Unsaturated isocyanides, too, have been the focus of considerable attention. Vinyl isocyanides have been prepared either by Cu20-catalysed isomerisation of allylic analogues or by the Schollkopf method of reacting aldehydes with situ metallated methyl isocyanide followed by dehydration of the adducts.The... 

The most interesting reaction is the addition of octahydrido- to octavinyl-silsesquioxane (or its allyl analogue), which provides the opportunity to produce micro- and mesoporous materials (Scheme 46). 

Ally Sulphides and Selenides.—Preparative methods described for saturated sulphides may be used for the allyl analogues, and 1,2-phenylthio-shifts can be exploited. Scheme 14 illustrates some of the methods used, and applications for the separate synthesis of 1- and 2-(phenylthio)buta-l,3-dienes. Dehydrochlorination of adducts formed from trisubstituted alkenes and PhSCl yields allyl sulphides. ... 

The photoelectron spectra of ( -allyl)2M (M=Ni, Pt, Pd) and their methyl-allyl analogues have been recorded and assigned. Contrary to previous assignments, the HOMO of (7 -allyl)2Ni appears to be a ligand-localized non-bonding orbital. Detailed n.m.r. studies show that ( -l-CH8C3H4)aNi exists in solution as an unequal mixture of the four syn isomers (14>-(17). In contrast, cyclic... 

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