Gossypium cadinanes and their analogs: synthesis of lacinilene C, 2,7-dihydroxycadalene, and their methyl ethers

Isolation and synthesis of two antiproliferative calamenene-type sesquiterpenoids from Sterculia tavia from the Madagascar Rain Forest

“…The synthesis initially followed McCormick's method for the synthesis of lacinilene C methyl ether ( 10 ) from 2-methylanisole. 7 The literature procedure was modified by running the Grignard reaction to convert the known ketoester 4 to 5-isopropyl-5-(4-methoxy-3-methylphenyl)-dihydrofuran-2-one ( 6 ) at low temperature, which increased the yield of 6 from 20% to 42% and of the reduction byproduct 5 from 23% to 30%. Dihydrofuranone 6 was then converted to cycloalkene 7 , diol 8 , and ketone 9 as previously described, 7 except that conversion of 8 to 9 was carried out using the sulfur trioxide pyridine complex instead of the Swern oxidation originally used.…”

“…7 The literature procedure was modified by running the Grignard reaction to convert the known ketoester 4 to 5-isopropyl-5-(4-methoxy-3-methylphenyl)-dihydrofuran-2-one ( 6 ) at low temperature, which increased the yield of 6 from 20% to 42% and of the reduction byproduct 5 from 23% to 30%. Dihydrofuranone 6 was then converted to cycloalkene 7 , diol 8 , and ketone 9 as previously described, 7 except that conversion of 8 to 9 was carried out using the sulfur trioxide pyridine complex instead of the Swern oxidation originally used. 7 Oxidation of the carbon-carbon double bond of compound 10 to triol 13 could not be accomplished directly with osmium tetroxide in the presence of N-methylmorpholine N-oxide because of the electron deficient nature of the αβ-unsaturated double bond.…”

“…Dihydrofuranone 6 was then converted to cycloalkene 7 , diol 8 , and ketone 9 as previously described, 7 except that conversion of 8 to 9 was carried out using the sulfur trioxide pyridine complex instead of the Swern oxidation originally used. 7 Oxidation of the carbon-carbon double bond of compound 10 to triol 13 could not be accomplished directly with osmium tetroxide in the presence of N-methylmorpholine N-oxide because of the electron deficient nature of the αβ-unsaturated double bond. The ketone 10 was thus reduced to alcohol 11 8 by Luche reduction 9 in a yield of 90.3%.…”

Site‐selective Oxidative Dearomatization of Phenols and Naphthols into ortho‐Quinols or Epoxy ortho‐Quinols using Oxone as the Source of Dimethyldioxirane

“…asc.wiley-vch.de 11 j [22,23] could be synthesized by oxidative dearoamtization of 2-naphthol 10 j, in 72% yield. The total synthesis was accomplished in only 8 steps from commercially available 7-methoxy-2-naphthol (see SI) and to the best of our knowledge is the shortest up to date.…”

“…Moreover, the reaction of 2-naphthols 10 g-i, with an ester or aryl groups at C-1, also furnished ortho-quinols 11 g-i with good to excellent yields (76-99%). Finally, in order to demonstrate the usefulness of our methodology, the antibacterial natural product lacinilene C methyl ether COMMUNICATIONS asc.wiley-vch.de 11 j [22,23] could be synthesized by oxidative dearoamtization of 2-naphthol 10 j, in 72% yield. The total synthesis was accomplished in only 8 steps from commercially available 7-methoxy-2-naphthol (see SI) and to the best of our knowledge is the shortest up to date.…”