1-Bromo-2-methoxyvinyllithium: a useful bromoacetaldehyde anion equivalent from 1,1-dibromo-2-methoxyethene

4‐exo‐dig Cyclocarbopalladation: A Straightforward Synthesis of Cyclobutanediols from Acyclic γ‐Bromopropargylic Diols under Microwave Irradiation Conditions

“…[10] The product 15 was obtained in 84 % yield as a mixture of trans and cis stereoisomers in a 1:1 ratio and this mixture was easily separated by chromatography on silica gel. For the first experiments, diol 15trans was selected as the starting material in order to minimize the stereoelectronic interactions between the phenyl group on the double bond and the new incorporated triple bond or double bond that might -in 15cis, for example -prevent the efficiency of the final coupling and eventually the 6π-electrocyclization process.…”

Proton-ionizable crown compounds. 2. Synthesis, complexation properties, and structural studies of macrocyclic polyether-diester ligands containing a 4-hydroxypyridine subcyclic unit

“…These results are different from those found for the complexes of proton-ionizable ligand 1, which contains the triazole subcyclic unit. Ligand 1 formed a kinetically more stable complex with benzylamine (14.0 kcal/mol) than it (8) Davidson, R. B,; Bradshaw, J. S.; Jones, B. A.; Dailey, N. K.; Christensen, J. J.; Izatt, R. M.; Morin, F. G.; Grant, D. M. J. Chiral recognition by (S,S)-7 for the enantiomers of NapEtNH3C104 and (S,S)-12 and {Rfi)-13 for both the enantiomers of NapEtNH3C104 and NapEtNH2 is shown by the data in Table III.…”

“…The S,S ligands formed kinetically more stable complexes with the R form of the amine or ammonium salt as was the case for other S,S-pyridino diester crowns.8,9 Ligand (R,R)-13 formed more stable complexes with the S form of the amine or salt as did the unsubstituted /?,i?-pyridino crown. 8 The degree of chiral recognition does not seem to depend on the size of the substituent. Dimethyl-substituted ligands 7 and 12 show greater chiral recognition for the R form of the ammonium salt (1.4 and 1.1 kcal/mol difference, respectively) than diphenyl-substituted ligand 13 does for the S ammonium salt (0.3 kcal/mol difference).…”

“…The dichloromethane was evaporated to give a yellowish solid (19.7 g). The crude product was recrystallized from acetone to give 17 as white crystals: 15.95 g (81%); mp 120-121.5 °C; IR (KBr) 1710,1740 cm'1; XH NMR (CDC13) 8 1.48-2.08 (m, 6 H), 3.50-3.84 (m, 2 H), 4.01 (s, 6 H), 5.69 (s, 1 H), 7.95 (s, 2 H). Anal.…”

“…The solid was recrystallized from acidified methanol to yield compound 3: 0.5 g (5.4%); mp [139][140] °C; IR (KBr) 1720 cm'1; XH NMR (CDC13) 8 3.90 (m, 8 H, OCH2), 4.44 (m, 4 H, COOCH2), 5.20 (s, 2 H, PhCtf2), 7.40 (s, 5 H), 7.76 The extraction was then continued for 3 days. The second batch of heptane was evaporated, yielding compound 10 as a waxy solid: 1.48 g (8.3%); mp 158-168 °C; IR (film) 1720, 1740 cm'1; lH NMR (CDC13) 8 3.3-3.9 (m, 16 H, OCH2), 4.40 (4). The benzyl-blocked ester 16 (10.0 g, 0.033 mol) and 6.45 g (0.033 mol) of tetraethylene glycol were used.…”