Macrocyclic triene

This isomerization of a Z to a E double bond by double sigmatropic rearrangement was also used for stereochemical control of a macrocyclic triene required in a steroid synthesis43. 

A novel triolefin ligand (E,E,E)-l,6,ll-tris[(2,4,6-triisopropylphenyl)sul-fonyl]-l,6,ll-triazacyclopentadeca-3,8,13-triene was anchored to a polystyrene support [47] (Scheme 9). Thus, the 15-membered triene 24 bearing a styrene group underwent polymerization with styrene and DVB to afford the cross-linked PS-supported cyclic triene 25. The supported macrocyclic triene 25 was treated with Pd(PPh3)4 to give the palladium complex 26. The complex... 

The first example of successful diene-diene RCM to construct a macrocyclic conjugated triene was disclosed by Wang and Porco in the first total synthesis of oximidine II (258) [121]. Oximidine II belongs to the family of salicylate en-... 

The X-ray structure of a mono-pyridyl containing pentaaza crown macrocycle (3,6,9,12-tetra-methyl-3,6,9,12,18-penta-azabicyclo[12.3.1]octadeca-l(18),14,16-triene) with zinc perchlorate has been determined.71 ... 

Mn(II) ions complexed by porphyrinato(2 ) ligands have shown catalytic superoxide anion dismutation. One SOD mimic, M40403, complexes Mn(II) via a macrocyclic ligand, 1,4,7,10,13-pentaazacyclopentadecane, containing added bis(cyclohexyl) and pyridyl functionalities. M40403 carries the systematic name [manganese(II) dichloro] 4R,9R, 14/s, 19/ )-3,10,13,20,26-pentaazatetracyclo[20.3. 1.0(4,9)0(14,19)]hexacosa-l(26),-22(23),24-triene ]. The molecule is shown in... 

DR. RALPH WILKINS (New Mexico State University) What is the rate of the reaction of trien with your copper macrocyclic tetrapeptide complex Based on your mechanism it should be... 

DR. MARGERUM Yes. I didn t show those data but we have a system in which a macrocyclic tetrapeptide is coordinated to copper and we have looked at its reaction with trien [Rybka, J. S. Margerum, D. W. Inorg. Chem. 1980, 19, 2784]. The trien will not react until we protonate a group, even in basic solu-... 

DR. MARGERUM Right. The macrocyclic complex first adds a proton following which trien reacts to form a mixed complex. The latter species then reacts with solvent to become further protonated before trien replaces the cyclic peptide. 

The first example of successful diene-diene RCM to construct a macrocyclic conjugated triene, was disclosed... 

In the case of an approach toward cytotrienins, Panek and coworkers achieved different chemoselectivity according to the catalyst they employed [22]. They first tried RCM of polyene 21 with catalyst G2 (Scheme 2.9). Unexpectedly, only the macrocyclic conjugated diene 22 is obtained presumably, initiation of the metathesis reaction occurs at the internal bond of one of the dienes. On the other hand, use of catalyst G1 leads to the expected conjugated triene 23 in 73% yield. 

In order to optimize the antitumoral properties of radicicol, particularly in vivo, the same group synthesized the analogous cycloproparadicicol, where the epoxide function is replaced by a cyclopropane [64]. Submitted to the conditions of the previous RCM reaction (CH2C12, 42°C, 19h), cydopropyl triene 94 leads to the expected macrolide 95 in only 16% yield, along with 30% of the corresponding 28-membered dimeric macrocycle (Scheme 2.37). After numerous assays, the best conditions tested (toluene, 110 °C, 10 min) brought the yield up to 55%. In this case, the balance between thermodynamic and kinetic factors seems decisive for the course of the reaction. The fact that the monomeric product is predominant at elevated temperature indicates that this form is entropically favored. 

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