A concise and general entry into (R)-4-hydroxy-2-substituted cyclopent-2-enones fromD-glucose: chiral intermediates for the synthesis of PGE₂, (–)-pentenomycin I, and allethrin

A Ratiometric Fluorescent Probe for Biological Signaling Molecule H2S: Fast Response and High Selectivity

“…Fifteen years later, Piccolo's team obtained either traces or about 20 % yields of this aldehyde when using either Pd(PPh 3 ) 4 or the Pd 2 (dba) 3 · CHCl 3 /butane‐2,3‐diylbis(diphenylphosphane) complex as catalysts 83. Pd(PPh 3 ) 4 was, nevertheless, effective in producing α,β‐unsaturated aldehydes either from a carbohydrate‐derived vinylic epoxide or from myrcene‐1,2‐epoxide, as shown in Equations (51)84,85 and (52),86 respectively. …”

Pd‐Mediated Reactions of Epoxides

“…[85,87] The steps leading to the intermediate 17B are similar to those previously suggested by Noyori's team for the isomerization of cyclic 1,3-diene mono-epoxides into β,γ-unsaturated ketones. [88] In fact, the β,γ-unsaturated aldehyde can also be isolated, as shown in Equation (53).…”

“…[82] Fifteen years later, Piccolo's team obtained either traces or about 20 % yields of this aldehyde when using either Pd(PPh 3 ) 4 or the Pd 2 (dba) 3 ·CHCl 3 /butane-2,3-diylbis(diphenylphosphane) complex as catalysts. [83] Pd(PPh 3 ) 4 was, nevertheless, effective in producing α,β-unsaturated aldehydes either from a carbohydrate-derived vinylic epoxide or from myrcene-1,2-epoxide, as shown in Equations (51) [84,85] and (52), [86] respectively.…”

“…[121] When the reaction was carried out under catalytic conditions [Equation (83)], we presume that the presence of the Cu II salt disfavors the oxidation step, as observed by Blackburn and Schwartz. [43] These couplings were subsequently carried out with aryl or vinylic halides and triflates in place of the organic mercurials [Equations (84), (85), and (86)]. [123,124] It should be noted that similar compounds can be obtained with the aid of Pd catalysis and 1-alkenylboranes [73,125] or aryl-and vinylstannanes, [126] but these reactions usually firstly involve the formation of an η 3 -allylpalladium complex such as 13A (see Scheme 13, path d) [126][127][128] rather than the aryl-or vinylpalladation of the C=C unit (Scheme 16).…”

Synthesis of 3,4-disaccharides from pyranosides and furanosides monomers, a novel class of potential bioactive disaccharides

“…Employing pyranoside 3 in a reverse reaction setup, no disaccharide formation could be observed via nucleophilic substitution of the tosyl residue in 6 19 nor triflate residue in 7. 20 . It can be assumed that steric hindrance at C-3 of the furanoside 6 and 7 is responsible for the unsuccessful reaction.…”