Palladium-catalyzed three carbon chain extension reactions with acrolein acetals. A convenient synthesis of conjugated dienals

Abstract

benzoic acid (170 mg, 0.93 mmol, 7%), identified in the same way. The third fraction was a pale yellow syrup that did not crystallize but was analytically pure (2.30 g, 8.03 mmol, 57%): 1H NMR (CDC13) 3.53 (br s, 3, 2-OCH3), 3.86 (s, 3, (m, 6, Ar H). When the NMR probe was heated to 100 °C the resonance at 3.53 became a sharp singlet.

An Interrupted Vinylogous Iso-Nazarov Reaction: Cycloisomerization of Conjugated Trienones to Cyclopenta[b]furan Derivatives

“…All of the unsaturated aldehydes employed to prepare dicarbonyl substrates 4 , except most of the deuterated analogues, are either commercially available or have been previously prepared in the literature. − The unsaturated precursors 4a , 4b , 4f , 4i , 4l , 4q , and 5l have been previously prepared by our group. , In the NMR data, the labels * and ** indicate that the labeled assignments are exchangeable.…”

Synthesis of (±)-(E,E)-2,7-Dimethylocta-2,4-dienedioic Acid

“…As test of this concept, freshly purified 4 was exposed to the above reducing medium containing AcOH catalyst. This led to the formation of acetal 11 [7], acetal 6, and aldehydic acid ester 7 in a 14 : 4 : 1 ratio, reminiscent of the results of the reduction of aged 4. The presence of the acid causes acceleration of the masking of the aldehyde carbonyl group, hence preventing its reduction and liberation of alcohol 5.…”

Synthesis and photochromic properties of novel yellow developing photochromic compounds

“…5-Methoxy-2-(4-methoxyphenyl)thiazole 5 was obtained from N-(4-methoxybenzoyl) glycine methyl ester as a yellow solid in 80% yield. Compound 3a was synthesized by the coupling reaction of 7 and 2-bromo-3-methyl-2-butene, 26 and was purified by HPLC. The structures of all compounds were confirmed by 1 H NMR, mass spectroscopy, and elemental analysis.…”