01084nas a2200169   4500008004100000022001400041245017100055210006900226260007100295300001400366490000700380520032600387100001900713700002300732700002900755856013000784       2009                        eng d  a1523-706000aStereoselective one-step construction of vicinal quaternary and tertiary stereocenters of the 5,10b-ethanophenanthridine skeleton: total synthesis of (+/-)-maritidine0 aStereoselective onestep construction of vicinal quaternary and t  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJUN  a2547-25500 v113 a<p>The challenging vicinal quaternary and tertiary stereocenters of the 5,10b-ethanophenanthridine skeleton are created in a single step utilizing intramolecular [3 + 2]-cycloaddition of nonstabilized azomethine ylide as the key step. The application of the chemistry is demonstrated by synthesizing (+/-)-maritidine.</p>1 aPandey, Ganesh1 aGupta, Nishant, R.1 aPimpalpalle, Tukaram, M.  uhttps://library.ncl.res.in/content/stereoselective-one-step-construction-vicinal-quaternary-and-tertiary-stereocenters-510b-001511nas a2200217   4500008004100000022001400041245018200055210006900237260007700306300001200383520061700395653001401012653002201026653001801048653002101066653001101087100001901098700002301117700002101140856013201161       2011                        eng d  a1434-193X00aConstruction of the 5,10b-phenanthridine skeleton using [3+2]-cycloaddition of a non-stabilized azomethine ylide: total synthesis of (+/-)-maritidine and (+/-)-crinine alkaloids0 aConstruction of the 510bphenanthridine skeleton using 32cycloadd  aPO BOX 10 11 61, D-69451 WEINHEIM, GERMANYbWILEY-V C H VERLAG GMBHcFEB  a740-7503 a<p>Vicinal quaternary and tertiary stereocenters of the 5,10b-phenanthridine skeleton 1 are constructed simultaneously in one step by the [3+2]-cycloaddition of non-stabilized azomethine ylide 9, generated by sequential double desilylation of 10 utilizing silver(I) fluoride as a one-electron oxidant. The regioas well as stereochemical origin of this cycloaddition reaction is explained through a favorable transition state 9''. The strategy is successfully applied for the total synthesis of the biologically active alkaloids (+/-)-maritidine (1a), (+/-)-crinine (1b), and their analogues (1d, 1e, and 1f).</p>10aalkaloids10aAzomethine ylides10aCycloaddition10aNatural products10aYlides1 aPandey, Ganesh1 aGupta, Nishant, R.1 aGadre, Smita, R.  uhttps://library.ncl.res.in/content/construction-510b-phenanthridine-skeleton-using-32-cycloaddition-non-stabilized-azomethine-0