Additions to bicyclic olefins. IV. Facile reduction of labile epoxides of bicyclic olefins by lithium in ethylenediamine

Syntheses in the Isocamphane Series XLI [1]. Derivatives of Epoxyisocamphenilanic Acid, Epoxycamphene, and a New Access to 7-syn-Hydroxycamphene

“…A similar outcome has been reported by Gassman et al for the opening of 2,3-epoxy-1,7,7-trimethylbicyclo[2.2.1]heptane by trimethyl silyl cyanide/ZnI 2 [19]. With Zn/trimethylsilyl chloride/dichloromethane or Li /ethylenediamine [20], a three-component reaction mixture was obtained, although such a reduction of norbornene oxides without rearrangement has been reported [21]. By HPLC it was possible to isolate one single compound pure enough to elucidate its structure by spectroscopic methods.…”

Gold(I)‐Catalysis for the Synthesis of Terpenoids: From Intramolecular Cascades to Intermolecular Cycloadditions

“…On the other hand, epoxidation of 88 with dimethyldioxirane gave 90 stereoselectivily (Scheme ). Epoxide opening and debenzylation of 90 was performed in the presence of Li in ethylenediamine to give (−)‐4β,7α‐aromadendranediol ( 84 ) in 96 : 4 er, which gave enantiopure compound after crystallization. The enantioselective synthesis of the natural products 83 and 84 was thus achieved in just seven steps with 12 % and 15 % overall yield, respectively.…”

“…We initially examined the intramolecular reaction of substrates as 96 in which the 1,6‐enyne and the alkene are tethered trough a siloxane (Scheme ) . After treatment of the crude product with HF⋅Py, diol 97 was isolated as a single crystalline stereoisomer in a reaction that proceeds through a enyne cyclization, 1,5‐OR shift to form 98 , followed by an intramolecular cyclopropanation to afford nine‐membered ring siloxane 99 .…”

“…Although the intramolecular approach could be carried forward to afford racemic schisanwilsonene A ( 92 ), a more practical intermolecular approach was developed to provide the enantioenriched material. Thus, reaction of 1,6‐enyne 100 with the bis TBS ether of 2‐methylenepropane‐1,3‐diol in the presence of [(JohnPhos)Au(MeCN)]SbF 6 at 23 °C led to 101 in good yield with a moderate loss of enantiomeric ratio (from 96 : 4 to 91 : 9) (Scheme ) . Functional group interconversion furnished 102 , which was oxidized to the aldehyde and then immediately treated with triphenylphosphonium methylide to furnish 103 .…”

“…The gold(I)‐catalyzed reaction 108 with the bis‐TBS ether of 2‐methylenepropane‐1,3‐diol, followed by desilylation, gave rise to diol 109 without detectable racemization. In the racemic series, diol 109 had been converted into (+)‐schisanwilsonene A ( 92 ) …”