Enantioselective route to a key intermediate in the total synthesis of forskolin

Lipase‐Catalyzed Domino Dynamic Kinetic Resolution of Racemic 3‐Vinylcyclohex‐2‐en‐1‐ols/Intramolecular Diels–Alder Reaction: One‐Pot Synthesis of Optically Active Polysubstituted Decalins

“…Herein we present the first lipase‐catalyzed domino process that combines the DKR of racemic alcohols 2 by using functionalized ethoxyvinyl esters 3 and the Diels–Alder reaction of the intermediates ( R )‐ 4 . The finding that the ruthenium catalysts ( 1 f and 1 g ) produced a fast racemization of the slow‐reacting enantiomers ( S )‐ 2 with reduced formation of the side products 6 was the key to the success of this process, and the products 5 , useful chiral intermediates for natural products such as compactin10 and forskolin,11 were directly obtained with up to 95 % ee in 81 % yield (Scheme ).…”

Absolute stereochemistries and total synthesis of (+)-arisugacins A and B, potent, orally bioactive and selective inhibitors of acetylcholinesterase

“…30 The known CBS reduction procedure was not feasible in our case because of poor reproducibility and the need for a large amount of expensive catalyst. 31,32 On the other hand, asymmetric hydrogenation using a ruthenium catalyst can be conducted easily on a preparative scale with a S/C ratio up to 500 and a substrate concentration as high as 2.5 M in 2-propanol. 33 When the achiral cyclic enone 14 was hydrogenated with a catalyst system containing was obtained in 90% ee and 97% yield.…”

“…Finally, by optical rotation, we determined that the absolute configuration of (2)-15 is S (Scheme 4). 31 The lactol 12, a coupling unit, was prepared in four steps starting from the chiral building block 15. Esterification of 15 with 2-butynoic acid to produce 17 followed by an intramolecular Diels -Alder reaction generated 13, which was treated with m-CPBA to stereoselectively produce the epoxide 18.…”

Lipase‐Catalyzed Domino Dynamic Kinetic Resolution of Racemic 3‐Vinylcyclohex‐2‐en‐1‐ols/Intramolecular Diels–Alder Reaction: One‐Pot Synthesis of Optically Active Polysubstituted Decalins

“…The finding that the ruthenium catalysts (1 f and 1 g) produced a fast racemization of the slow-reacting enantiomers (S)-2 with reduced formation of the side products 6 was the key to the success of this process, and the products 5, useful chiral intermediates for natural products such as compactin [10] and forskolin, [11] were directly obtained with up to 95 % ee in 81 % yield (Scheme 1).…”