Total synthesis of palmyrolide A and its 5,7-epi isomers

Stereoselective Total Synthesis of the Marine Macrolide Sanctolide A

“…Accordingly, acid 10 was coupled with alcohol 9 under Yamaguchi's conditions15 at room temperature to provide ester 8 in 90 % yield (Scheme ). The removal of the silyl group with tetra‐ n ‐butylammonium fluoride (TBAF) afforded alcohol 21 , which was oxidized into acid 22 in 90 % overall yield through a two‐step sequence that involved DMP11a and Pinnick16 oxidations. Our attempt for a one‐step oxidation of alcohol 21 into acid 22 by employing 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) and [bis(acetoxy)iodo]benzene (BAIB) resulted in poor yields (60 % yield).…”

“…The benzyl protecting group was smoothly removed by using Pd/C in ethyl acetate under hydrogen to yield alcohol 23 in 98 % yield. A DMP oxidation of 23 followed by treatment with trifluoroacetic acid (TFA)16 in benzene at reflux temperature for 72 h furnished the target compound sanctolide A (Scheme ). The analytical data of the synthetic compound was in full agreement with that of the isolated natural product,3 with the exception of a small variation in the optical rotation values [observed optical rotation for synthetic compound is [ α ] D 20 = –38.5 ( c = 0.035, MeOH) and that for the isolated natural product is [ α ] D 20 = –41 ( c = 0.1, MeOH)] 3.…”

Asymmetric Total Synthesis of 16‐Methyleicos‐(4E)‐en‐1‐yn‐3‐ol from the Marine Sponge Cribrochalina vasculum: Establishment of Absolute Configuration of Chiral Centers

“…It was converted into monosubstituted TBS ether 6 and subsequent oxidation of primary alcohol with BAIB ((bisacetoxyiodo) benzene), TEMPO ((2, 2, 6, 6‐tetramethylpipe ridin‐1‐yl) oxyl) and CH 3 CN in water (3:1) provided the acid 7 . The acid was transformed to 4‐benzyl‐2‐oxazolidinone derivatives 9a and 9b with Evans auxiliaries 8 a and 8 b using pivaloyl chloride, LiCl and TEA. The enantioslective methylation of 9 a and 9 b using CH 3 I and NaHMDS afforded the corresponding methylated products 10 a (dr=92:8) and 10 b (dr=95:5).…”

Total Synthesis of Desmethyl Jahanyne and Its Lipo-Tetrapeptide Conjugates Derived from Parent Skeleton as BCL-2-Mediated Apoptosis-Inducing Agents

“…A column chromatographic separation allowed isolation of pure 16 . 17 Exposure of 16 to tetra- n -butylammonium fluoride (TBAF) allowed the cleavage of TMS in acetylenic functionality to generate free alkyne 17 in 93% yield, which upon hydrolysis with LiOH/H 2 O 2 provided the acid unit 2 of jahanyne in 90% yield. 18 The executed route ( Scheme 1 ) allowed us to synthesize gram quantities of lipophilic end of jahanyne toward total synthesis.…”