This method facilitates the construction of cis‐1,4‐silaketals (n=0, d.r.=20:1; see scheme), whereas the extension of this concept to higher alkenyl alcohols (n=1–4) results in a reversal of diastereoselectivity that favors formation of the trans isomer.P. Andrew Evans...
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Finally, reductive cleavage of the cobalt complex and hydrogenation of the double bonds afforded the target (+)-cis-lauthisan 72, αD25=+4.1(c 0.9, CHCl3). Sign in to download full-size image Scheme 8. The synthesis of polycyclic ethers with variable ring sizes can be conducted by two...
be run at high dilution, and does not require starting materials that include covalent conformational constraints. In addition to these needs, it is also desirable that the method yield functionalized cyclic olefins with a definite stereo-chemistry at the olefin bond; preferably, a cis conformation....
14.A process according to claim 1, wherein in the compounds of formulas (I) and (III):RAis —OSO2—R27, wherein R27is p-bromophenyl;R3is NH—C(O)—OR20, wherein R20is cyclopentyl;R4is H;D is a 5 atom all carbon chain containing one cis double bond at position 13,14; and ...
cis(E:Z)ratiowasobservedwithmoderatetohighoverallyield.ConcentrationdependentfluorescencespectrawereobservedforCMBLswithlongerlinkers(n=3),whereasconcentrationindependentspectrawereobservedforCMBLswithshorterlinkerlength(n=2and/or1)withamarkedexceptionin(E)-alkene6a.Concomitantchangesinabsorptionaswellfluorescence...
describe a new approach to long-range asymmetric induction using the diastereoselective temporary silicon-tethered (TST) ring-closing-metathesis (RCM) reaction of mixed bisalkoxy silanes 1, derived from an allylic and prochiral alcohol, for the construction of cis-1,4-silaketals 2 (Scheme 1; n...
FIG. 3: Structures of non-limiting examples of suitable catalysts for a ring-closing metathesis reaction.FIG. 4: Scheme showing a non-limiting example of the three-step method to produce C11, C12, and C13 lactams.FIG. 5: Non-limiting example of step 1, amide formation of 9-decenoic acid...