Total synthesis of (±)-eremolactone

Synthetic studies towards naturally occurring γ-(Z)/(E)-alkylidenebutenolides through bimetallic cascade cyclization and an adventitious photoisomerization method

“…Chemical shifts are shown in δ. 13 C NMR spectra were recorded with a complete proton decoupling environment. The chemical shift values are listed as δ H and δ C for 1 H and 13 C, respectively.…”

“…After the formation of the maximum amount of the desired compound as monitored by TLC analysis, the mixture was then concentrated under reduced pressure and the crude product was purified through flash column chromatography (EtOAc : hexane (m, 2H), 6.81-6.72 (m, 1H), 6.33 (dd, J = 5.6, 1.9 Hz, 1H), 3.87 (s, 3H). 13 The compound was synthesized by following a general procedure for bimetallic cascade cyclization as described earlier from 1-bromo-2-ethynylbenzene and Z-3-bromoacrylic acid to afford 204 mg (80%) of 3i as a liquid. 1 H NMR (500 MHz, CDCl 3 ) δ: 8.17 Compound 3k was prepared from 5-methylhex-1-yn-3-ol following the general procedure of bimetallic cascade cyclization in 80% yield.…”

Nucleophilic Addition–Electrophilic Coupling with a Carbanion Intermediate

“…Common examples include 2-phenylthio-88 and 2-phenylselenyl-2-cyclopentenone. 89 Enantiomerically pure 2-arylsulfinyl-2-cycloalkenones offer additional, directable diastereofacial bias during difunctionalization to produce cycloalkanones of high enantiomeric purities (equation 18; NMP, N-methyl-2-pyrrolidone).9o Substituents at the a-position of the substrate which activate it toward conjugate addition can promote regiospecific attack of the Michael donor when other competing modes of conjugate addition are possible (equation 19). 91 Cycloalkenones are intrinsically less reactive than non-J3-substituted acyclic enones.…”

“…65 ,105,174,175 1,4-Addition-initiated vicinal difunctionalizations generally predominate, as exemplified in equation (40). 174 Related substrates (19) and (20), wherein one of the two double bonds in a conjugated alkadienoate is replaced by a cyclopropyl moiety, undergo net 2,6-dialkylation and 2,3-dialkylation, respectively (equations 41 and 42).176 …”

Asymmetric baker’s yeast reductions of bridgehead-substituted bicyclo[2.2.2]octane-2,6-dione derivatives followed by conversion into catalytically active BODOLs for the diethylzinc addition to benzaldehyde

“…Bicyclo [2.2.2]octanes are often found as subunits in natural products [1][2][3][4][5][6][7][8] and they are frequently used as important building blocks in total synthesis [9][10][11][12][13][14][15] and as ligands in asymmetric catalysis. [16][17][18][19][20][21][22][23][24][25] New applications for bicyclo [2.2.2]octanes are presented continuously.…”