NHC-catalyzed cleavage of vicinal diketones and triketones followed by insertion of enones and ynones

• Ken Takaki,
• Makoto Hino,
• Akira Ohno,
• Kimihiro Komeyama,
• Hiroto Yoshida and
• Hiroshi Fukuoka

Beilstein J. Org. Chem. 2017, 13, 1816–1822, doi:10.3762/bjoc.13.176

• , the reaction efficiency was much lower than that of benzil (1a) (Scheme 4). The only isolated by-product in the reaction of 5a was bicyclo[3.2.1]octanone 8 (ca. 10%), which was formed by competitive tandem Michael–aldol reaction [21]. Cycloheptane-1,2-dione (5b) and cyclododecane-1,2-dione (5c) gave

The difluoromethylene (CF₂) group in aliphatic chains: Synthesis and conformational preference of palmitic acids and nonadecane containing CF₂ groups

• Yi Wang,
• Ricardo Callejo,
• Alexandra M. Z. Slawin and
• David O’Hagan

Beilstein J. Org. Chem. 2014, 10, 18–25, doi:10.3762/bjoc.10.4

• hydrogen atoms, raises the energy of such conformations. For cyclododecane, placing the CF2 groups 1,4 (3) or 1,7 (4) to each other, stabilizes the [3.3.3.3] square like conformation of the ring. However if the CF2 groups are placed 1,6 to each other as in 5, this introduces considerable distortion of the

The preferred conformation of erythro- and threo-1,2-difluorocyclododecanes

• Yi Wang,
• Peer Kirsch,
• Tomas Lebl,
• Alexandra M. Z. Slawin and
• David O'Hagan

Beilstein J. Org. Chem. 2012, 8, 1271–1278, doi:10.3762/bjoc.8.143

• Yi Wang Peer Kirsch Tomas Lebl Alexandra M. Z. Slawin David O'Hagan EastChem School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK Merck KGaA, Frankfurter Str. 250, 64293 Darmstadt, Germany 10.3762/bjoc.8.143 Abstract Cyclododecane adopts a square-like structure with corner and

• –F bond endo into the ring, and appear to benefit from C–CHF–C angle widening, which relaxes 1,4-H,H transannular interactions. Keywords: alicyclic chemistry; conformational analysis; cyclododecane; 19F NMR; organo-fluorine chemistry; transannular interactions; Introduction The conformation of

• cyclododecane (1) in the solid state was first reported by Dunitz and Shearer in 1960 [1][2]. They showed that cyclododecane has a square topology, which can be classified as a [3333] type structure [3][4]. Their conclusion was derived from X-ray diffraction data, which could not fully resolve the structure due

Part 2. Mechanistic aspects of the reduction of S-alkyl- thionocarbonates in the presence of triethylborane and air

• Florent Allais,
• Jean Boivin and
• Van Tai Nguyen

Beilstein J. Org. Chem. 2007, 3, No. 46, doi:10.1186/1860-5397-3-46

• from cyclododecanol afforded cyclododecane in a remarkable 62% yield. No hypothesis about the origin of the hydrogen atom that replaced the original xanthate function was proposed. Recently, as the work reported here was largely completed as already mentioned in the first part of this series,[3][4