Stereoselectivity of Macrocyclic Ring-Closing Olefin Metathesis

Abstract

[reaction: see text] Macrocyclic ring-closing olefin metathesis using ruthenium catalyst 3 was performed to produce a 14-membered lactone. The E/Z ratio of lactone was high regardless of the R group (auxiliary) or the initial alkene stereochemistry. A kinetic study demonstrates that the high E/Z ratio is due to secondary metathesis reactions that isomerize the product to the thermodynamic E/Z ratio.

Recent Methods for the Synthesis of (E)‐Alkene Units in Macrocyclic Natural Products

“…[25] By submitting 17 to a more active catalyst, a higher proportion of the E isomer of lactone 18 was produced. The E/Z ratio does not significantly change with time when catalyst 7 is used, but it increases from 4.8:1 at 20 % conversion to 11.5:1 at 100 % conversion with 10.…”

Tandem Catalysis: The Sequential Mediation of Olefin Metathesis, Hydrogenation, and Hydrogen Transfer with Single-Component Ru Complexes

“…Complexes (PCy 3 ) 2 Cl 2 Ru=CHPh (1) 1 and (H 2 IMes)(PCy 3 )Cl 2 Ru=CHPh (2) 2 and substrates 1,6-heptadien-4-one (6), 3 1,8-nonadien-5-one (12), 4 2-allyl-2-(2-methyl-allyl)-malonic acid diethyl ester (15), 5 1,4-bis-allyloxy-but-2-yne (21), 4 2-methyl-acrylic acid but-3-enyl ester (24), 6 N-allyl-N-isopropyl-acrylamide (27), 7 and undec-10-enoic acid but-3-enyl ester (30) 8 were prepared as previously reported.…”

“…Substrates 4,4-dicarbethoxycyclopentene (4), 2 cyclopent-3-enone (7), cyclopent-3-enol (10), 2 cyclohept-4-enone (13), 4,4-dicarbethoxy-1-methylcyclopentene (16), 5 2,5,2',5'-tetrahydro- [3,3']bifuranyl (22), 9 3-methyl-5,6-dihydro-pyran-2-one (25), 6 1-isopropyl-1,5-dihydro-pyrrol-2-one (28), 10 oxacyclotetradec-11-en-2-one (31), 8 acetic acid 4-phenyl-but-2-enyl ester (33), 11 acetic acid 7-oxo-oct-5-enyl ester (35), 6 4-phenyl-but-3-en-2-one (37), 12 and 3-(4-chloro-phenyl)-acrylic acid methyl ester S2 (39) 12 are known metathesis products. 1 H (300 MHz) and 13 D were determined on a Jasco Model P-1010 polarimeter in methanol and are given in 10 -1 deg cm 2 g -1 .…”

Development of Environmentally Benign Organometallic Catalysis for Drug Discovery and Its Application

“…[54][55][56][57][58][59][60][61][62][63][64] In the RCM of dienes 23 and 25 to the 14-membered lactam 26 and the 18-membered lactam 28, E-isomers are the major products. On the other hand, the RCM of 24 to the 16-membered ring lactam 27 gave a Z-isomer as the major product (Table 4).…”