Cyclopropanation with acyloxy chromium carbene complexes. A synthesis of (.+-.)-prostaglandin E2 methyl ester

1-Metalla-1,3,5-hexatrienes and Related Compounds

“…in connection with model reactions for the generation of prostaglandin derivatives (Scheme 32). [39] Scheme 34. π-Cyclization vs. α-cyclization of 6-amino-1-metalla-1,3,5-hexatrienes…”

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

“…Acyloxycarbene complexes 7 (eq 3), which are generated in situ, have been found more reactive than the alkoxy complexes (4) and readily react with enol ethers in the absence of CO pressure to give a variety of 1,2-dioxygenated cyclopropanes 8 in reasonable yields. 58 This has been used as the key step in the synthesis (eq 4) of (()-prostaglandin E 2 methyl ester 9. 58 Methyl(methoxymethylene)Cr(CO) 5 has successfully been used to cyclopropanate fullerene C 60 .…”

“…58 This has been used as the key step in the synthesis (eq 4) of (()-prostaglandin E 2 methyl ester 9. 58 Methyl(methoxymethylene)Cr(CO) 5 has successfully been used to cyclopropanate fullerene C 60 . 59 A single isomer of the methanofullerene from cyclopropanation of a 6,6 ring junction was obtained in 20% to >50% yields.…”

Glycosylidene Carbenes. Part 24 Reactivity modulation by protecting groups of the addition of glycosylidene carbenes to electron‐rich alkenes

“…RO-C(6) has a weak influence on the energy of the frontier orbitals. Calculation of the frontier-orbital energies of the enol ethers 15,6,10,24, and E shows that the HOMO of the 2,3-dihydro-5-methylfuran 15 is lower in energy than the HOMO of the other enol ethers and that the LUMO of the dihydrofurans 15 and 6 is lower than the LUMO of Table 3) for these carbenes and enol ethers are smaller than the AEN values (E, electrophilic interaction; N, nucleophilic interaction). This is in keeping with the assumption that the reaction is initiated by a dominant electrophilic interaction between the carbenes and the enol ethers.…”

“…Only few examples for the addition of alkoxy carbenes (see [12] and refs. quoted therein), alkoxyalkyl carbenes [13], and alkoxyalkyl carbenoids [14] [15] to enol ethers are known, while the addition of mono-and dihalo carbenes to enol ethers, including glycals [16] [17], is amply documented.…”