α-amino esters 9a,b yielded (4′S,9a′R)-14a (≡15a) and (4′S,9a′R)-14b (≡15b), (4′S,7′S,9a′R)-14c and (4′R*,7′S*,9a′S*)-15c. The formation of compounds with three stereogenic centers 14c and 15c was accompanied by partial racemization. The versatility of the reported reaction sequence is limited by the steric availability of the secondary amino group in the intermediates 4, 9 and 10, as well as in the
Versatile synthesis of bicyclo[4.3.0]nonenes and bicyclo[4.4.0]decenes by a domino Heck-Diels-Alder reaction
作者:Kiah How Ang、Stefan Bräse、Arno G. Steinig、Frank E. Meyer、Amadeu Llebaria、Katharina Voigt、Armin de Meijere
DOI:10.1016/0040-4020(96)00639-4
日期:1996.8
afterwards in a one-pot process) to give bicyclo[4.3.0]nonene and bicyclo[4.4.0]-decene derivatives in good to excellent yields. Among the examples reported are the first cases of intramolecular Heck reactions with a (bromomethylene)cyclopropane starter or/and a methylenecyclopropane terminator which occur without ring opening of the cyclopropyl group.
Access to Variously Substituted 5,6,7,8-Tetrahydro-3H-quinazolin-4-ones via Diels–Alder Adducts of Phenyl Vinyl Sulfone to Cyclobutene-Annelated Pyrimidinones
作者:Suryakanta Dalai、Vladimir N. Belov、Shamil Nizamov、Karsten Rauch、Dirk Finsinger、Armin de Meijere
DOI:10.1002/ejoc.200600060
日期:2006.6
elimination of methanol to afford the cyclobutene-annelated pyrimidinones 6 in 43–83 % yield (7 examples). Thermal cyclobutene-ring opening of the latter at 175 °C followed by regioselective Diels–Alder cycloaddition with phenyl vinylsulfone gives the 2-aryl-6-(phenylsulfonyl)-5,6,7,8-tetrahydroquinazolinone derivatives 12 in 39–83 % yield (7 examples). Base-induced elimination of benzenesulfinic acid and subsequent
Domino Reactions of Amidines with Methyl 2-Chloro-2-cyclopropylideneacetate as an Efficient Access to Cyclobutene-Annelated Pyrimidinones
作者:Marcus W. Nötzel、Karsten Rauch、Thomas Labahn、Armin de Meijere
DOI:10.1021/ol025530+
日期:2002.3.1
one-step synthesis of 2,4-diazabicyclo[4.2.0]octa-1(6),2-dien-5-ones 3 from methyl 2-chloro-2-cyclopropylideneacetate (1) and amidines 2a-c as well as N,N-dimethylguanidine (2d) is described. Similar to the benzocyclobutenes, the cyclobutene-annelated pyrimidones 3 undergo thermal ring opening and the resulting o-quinodimethaneanalogues readily cycloadd dienophiles to yield tetrahydroquinazolone derivatives
Addition of Indole to Methyl 2-Chloro-2-cyclopropylideneacetate en Route to Spirocyclopropanated Analogues of Demethoxyfumitremorgine C and Tadalafil
作者:Michael Limbach、Suryakanta Dalai、André Janssen、Mazen Es-Sayed、Jörg Magull、Armin de Meijere
DOI:10.1002/ejoc.200400617
日期:2005.2
Indole readily added across the double bond of the highly reactive Michael acceptor methyl2-chloro-2-cyclopropylideneacetate (4) to yield 2-chloro-2-(3′-indolylcyclopropyl)acetate 5 (85%) which was converted in two steps into the racemic tryptophan analogue 7 in 90% yield. This in turn was transformed by a condensation and Pictet−Spengler sequence into the spirocyclopropane analogues, 11, 13 and 15