A Ruthenium-Catalyzed, Novel and Facile Procedure for the Conversion of Vicinal Dihaloalkenes to α-Diketones

Synthesis of carbazole analogs via Grob fragmentation of norbornyl α-diketones

“…Observation of a single regioisomer 8 or 9 is due to the cleavage of front bond followed by the formation of half-chair intermediate, wherein the ester group occupies sterically less hindered pseudoequatorial position. 15 The ketoenols 8, 9 were smoothly converted to the corresponding Omethylated bi-phenyl derivatives 10 and 11 in two steps. First step involved in the treatment of freshly prepared diazomethane in methanol-ether solution at -10 to 0°C t o a f f o r d t h e Omethylated products.…”

Indium‐Mediated Regio‐ and Diastereoselective Reduction of Norbornyl α‐Diketones

“…The 1 H NMR spectra of lactones 19 and 20 feature three singlets due to OMe groups; in their 13 C NMR spectra the carbonyl groups give [a] Shift for exo Me. [17] using one equivalent of DIBAL-H at À78 8C, furnished a mixture (Scheme 3). The five-membered ring aldehyde 22 a, the bicyclic lactone 23, and the unreacted bis(a-chloro ester) cyclopentane derivative 21 a were formed in a ratio of 1.3:1:1.5, thus disqualifying this as a useful route to aldehyde 22 a.…”

“…[17] The tetrahalonorbornyl derivatives are easily accessible, and have been used as inextricable templates in organic synthesis. [18] The a-diketones were reduced by using indium metal (cut into small pieces) in MeOH/H 2 O (4:1) at reflux temperature in the presence of either NH 4 Cl, LiCl or NaCl (Table 1, Table 2, Table 5).…”

Synthesis and molecular assembly of benzenoid ring-mounted U-shaped septuple-bridged [7,7]orthocyclophanes walled by cofacial quinoxaline rings

“…1. 34 The process consists of three fundamental operations: (1) the DielseAlder reaction of 1,2,3,4-tetrachloro-5,5-dimethoxycyclopentadiene (TDCp, 2) 36 with a suitable bis-dienophile such as 3, 37 to construct a bisadduct as the central spacer scaffold, (2) the conversion of dichloroetheno-bridges in the bis-adduct by ruthenium-promoted oxidation using Khan's protocol 38 to generate a bis-a-diketone, followed by (3) the construction of sidewalls (phane parts) by the condensation of the bis-a-diketone with an arene-1,2-diamine (ADA, 4) to produce 1 (A) embedding face-to-face aligned quinoxaline (QX), benzoquinoxaline (BQX), dimethylquinoxaline (diMQX) or other substituted-QX rings. 33e35, 39,40 X-ray crystallographic analysis revealed that the pair of QX sidewalls in orthocyclophanes 1 (A) are stretching out from the rigid spacer scaffold in almost parallel (syn-periplanar) manner, separated by centroid-to-centroid distances of about 7.5e8.5 A.…”