Synthesis of olefins from sterically hindered alcohols by pyrolysis of thiocarbonate O-esters

Abstract

Sterically hindered alcohols e.g. (I; R = H) were acylated with O-4-methylphenyl chlorothioformate in high yield and the resulting thiocarbonates were converted into olefins by pyrolysis.

Fate of 1-adamantyl carbene. Evidence for the formation of the bridgehead olefin 3-homoadamantene

“…35% yield) was obtained from 2-adamantanecarboxaldehyde tosyldrazone and butyllithium followed by pyrolysis.7 The product proved to be identical with a sample prepared from adamantanone via 2-pentyl-2-adamantanol,4 mp 38.2-40°(treatment with n-pentyllithium 98% yield), 2-(n-pentylidene)adamantane4b (dehydration, 87% yield), and catalytic hydrogenation (PtOs, 4 atm, 82 % yield). (7) The decomposition of 2-adamantanecarboxyaldehyde tosylhydrazone lithium salt involves mainly a 1,2-hydrogen migration to give 2methyleneadamantane (48 % yield).…”

The Palladium-Catalyzed Enyne Cycloisomerization Reaction in a General Approach to the Asymmetric Syntheses of the Picrotoxane Sesquiterpenes. Part I. First-Generation Total Synthesis of Corianin and Formal Syntheses of Picrotoxinin and Picrotin

“…Realizing that steric approach of a base as required for trans-elimination not only must come from the concave face of the hydrindane but would also be impeded by the presence of the bridged lactone prompted us to investigate the possibility of effecting a cis-elimination. Thus, derivatization of the C8 hydroxyl group as the p -tolylthionocarbonate 36 was accomplished in 83% yield …”

Synthesis and reactions of two stereoisomeric [4.5.5.5]fenestranes with bridgehead substituents

“…1 H NMR: 3.00 (dd, J¼10.7, 5.5, 1H), 2.46 (s, 2H), 2.09e2.23 (st, 2H), 1.55e2.01 (st, 9H), 1.28 (s, 3H), 1.21 (s, 3H). 13 ]dodeca-2-one 17 9 . As described above, deprotection of 3 (0.797 g, 2.40 mmol) induced by 3.76 g (12.0 mmol, 5 equiv) in THF (80 mL) gave after work up and flash chromatography 10b (0.46 g, 88%) as colourless powder.…”

“…The multiplicities for the 13 Ce 1 H couplings were extracted from DEPT measurements, those for the 13 Ce 19 F interactions were apparent in the 13 C spectra. Mass spectra (MS), determined on a Varian MAT CH7A (70 eV, EI) and a Fisons Autospec Q spectrometer, are reported for selected peaks (intensities >10%) in units of m/z and in relative intensities to the base peak.…”