Total synthesis of (±)-heliannuol D, an allelochemical from Helianthus annuus

Effects of fused benzene rings on tautomerizations and inversions of benzo, azabenzo, and oxabenzocycloheptatrienes at theoretical levels

“…Similarly, derivatives of oxabenzocycloheptatrienes occur in natural products [21,22] and are used as natural herbicides [23]. Hence, studying tautomerization and inversions of these biologically and pharmacologically interesting compounds provides an opportunity to disclose new aspects of their structural behavior [16][17][18][19][20][21][22][23][24][25][26][27][28].…”

First asymmetric total synthesis of novel and cytotoxic 2′-R-hydroxylanneaquinol

“…The alcohol 11 was oxidized using iodoxybenzoic acid (IBX) in dry DMSO and dry CH 2 Cl 2 to afford the corresponding aldehyde in 95% yield (not isolated), which was subjected to a Wittig olefination 15 with nonyl tri phenyl phosphonium bromide in tetrahydrofuran-hexamethyl phosphoric acid triamide (THF-HMPA) and n-butyllithium at À78°C to afford Z-olefin 12 in 75% yield. Deprotection of the two aromatic methoxy groups in 12 was attempted using MeMgI, 16 TMSI, 17 NaSEt, 18 BBr 3 , 19 and PhSH/ K 2 CO 3 , 20 which all gave mixtures of products. However, the demethoxylation was achieved using CAN in 1:1 CH 3 CN-H 2 O medium to afford 1,4-quinone 13 in 85% yield.…”

Cationic Palladium‐Catalyzed [5+2] Annulation: Synthesis of 1‐Benzoxepines from 2‐Aroylmethoxyarylboronic Acids

“…of 2a still gave an 88 % yield of desired product 3aa. Furthermore, the [5 + 2] annulation was not catalyzed 2 /dppp under the same reaction conditions. This indicated that the cationic palladium complex has great advantages over the neutral one in this reaction.…”

“…[2] The simple and efficient synthesis of 1-benzoxepine derivatives is attractive in synthetic organic chemistry and medicinal chemistry. [3] We reported herein a new, efficient synthesis of 1-benzoxepines by cationic palladium-catalyzed tandem cyclization of 2-aroylmethoxyarylboronic acids (1) and alkynes (2) [Eq (1)] involving the addition of vinylpalladium species to ketones.…”

“…resulted in the rapid decomposition of 2a and none of the annulation product was detected. However, the use of insoluble bases, such as Ba(OH) 2 or Amberlite IRA-400 (OH), was found to give high yield of the normal product 3aa (90 % and 86 %, respectively, Table 1, entries 3 and 4). The yield of 3aa was also affected by the solvent.…”