Selective Synthesis of 1,3-Dienic Terpenes in a β-Form through Regioselective 1,4-Elimination of Allylic Ethers

Abstract

γ-Methyl-substituted allylic ethers proved to be converted into β-substituted dienes exclusively on treatment with t-BuOK in refluxing THF or cyclohexane.

Synthesis of Cordiaquinones B, C, J, and K on the Basis of a Bioinspired Approach and the Revision of the Relative Stereochemistry of Cordiaquinone C

“…The cyclization was carried out using as catalysts either a Lewis acid (homogeneous conditions) or zeolite NaY (heterogeneous conditions), depending on the nature of the reacting epoxide. The current results exemplify once more the valuable role of zeolite NaY as a unique, efficient, and highly useful acidic catalyst in epoxy terpene cyclization …”

“…trans , trans -Farnesol was protected as a THP ether ( 2 ) in 98% yield by reaction with 5 equiv of 3,4-dihydro-2 H -pyran in the presence of a catalytic amount of pyridinium p -toluenesulfonate (PPTS). The THP-protected farnesol 2 was treated with t -BuOK in THF, in the presence of a catalytic amount of 18-crown-6, and furnished exclusively ( E )-β-farnesene ( 3 ) in 86% yield. The epoxidation of 3 by reaction with N -chlorosuccinimide in THF/H 2 O followed by treatment of the resulting chlorohydrin with K 2 CO 3 in methanol yielded the naturally occurring epoxy ( E )-β-farnesene ( 4 ) in 77% overall yield as the only regioisomer.…”

Myrcene as a Natural Base Chemical in Sustainable Chemistry: A Critical Review

“…However, since decades these odoriferous alcohols are made industrially from myrcene (section 5.1) and an extraction of these alcohols from nature to generate myrcene is not economic, so that these reactions are rather model reactions. An elimination occurs at temperatures between 200-350 8C [60] or in the presence of strong bases, for example, KOH, [61] tBuOK, [62] or LiNiPr 2 .…”

“…However, since decades these odoriferous alcohols are made industrially from myrcene (section 5.1) and an extraction of these alcohols from nature to generate myrcene is not economic, so that these reactions are rather model reactions. An elimination occurs at temperatures between 200-350 8C [60] or in the presence of strong bases, for example, KOH, [61] tBuOK, [62] or LiNiPr 2 . [63] Zeolites [64] or transition-metal catalysts, for example, Pd(OAc) 2 /PPh 3 , [65] Mo(CO) 6 , [66] and Pd(PPh 3 ) 4 /Et 3 N, [67] are also able to generate dienes from alcohols and acetates.…”