Isomerization and functionalization of 2:1 Diels–Alder adducts of cyclopentadiene and p -benzoquinone: Applications to polycycles via ring-closing metathesis and ring-opening metathesis as key steps

Bidirectional Synthesis, Photophysical and Electrochemical Characterization of Polycyclic Quinones Using Benzocyclobutenes and Benzodicyclobutenes as Precursors

“…The IR spectrum revealed a characteristic band at ñ = 1671 cm À 1 for the C=O stretching vibration. The 1 H as well as the 13 C NMR spectrum are in full accord with the constitution of 26. On the other hand, the presence of two bromine atoms in 27 is verified from the isotopic molecular ion cluster at m/z = 584, 586 and 588 (1 : 2 : 1).…”

“…The IR spectrum showed a characteristic C=O stretching band at ñ = 1673 cm À 1 . However, the only available spectroscopic tool to identify whether the bromo substituents are located at the 2,9 or at the 2,10 positions in compound 27 was 13 C NMR spectroscopy, where one signal for the carbonyl carbon atoms would appear if the bromo substituents were located at the 2,9 positions, while two signal would be expected they were located at the 2,10 positions. Unfortunately, a well-resolved 13 C NMR spectrum could not be obtained due to the low solubility of compound 27 in almost all available deuterated solvents (CDCl 3 , acetone-d 6 , DMSO-d 6 ) even at elevated temperature (40 °C).…”

“…[8][9][10][11][12] Quinones were found to be typical electron poor dienophiles in cycloaddition reactions. [13][14][15][16][17] In addition, quinone structures are widely abundant in redox-active natural compounds associated with a number of biological processes like photosynthesis in plants and bacteria, [18][19][20] coenzyme Q functions, [21][22][23][24] vitamins K [25][26][27][28][29] and E [30][31][32] activities. They show marked anti-oxidant, [33][34] anti-inflammatory, [35][36][37] antibiotic, [38][39][40][41] and antitumoral [42][43][44][45] activities as well.…”

Design and Synthesis of Polycycles, Heterocycles, and Macrocycles via Strategic Utilization of Ring‐Closing Metathesis

“…An important approach was described toward the synthesis of various complex propellanes (e. g., 206 and 209 ) . The required building block 205 was derived from a readily accessible endo‐anti‐endo adduct 204 .…”

Synthesis of 4-oxatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione derivatives as lead scaffolds for neuroprotective agents

“…26 Cycloaddition reactions are common, and found to be useful in the formation of most norbornene-derived molecules, particularly the polycyclic-cage scaffolds. [32][33][34][35][36][37][38] These molecules are prominent scaffolds in improving the pharmacokinetic and pharmacological properties of active pharmaceutical substances. 19 Moreover, they display wide reactivity as substrates for various functional moeities, and, as such, are very useful and highly desirable synthetic intermediates in the field of organic and organometallic chemistry.…”