Unsaturated neopentyl compounds. The effect of methyl substitution on the acetolysis rates of homoallenic neopentyl-type brosylates

Alkyne versus Allene Activation in Platinum‐ and Gold‐Catalyzed Cycloisomerization of Hydroxylated 1,5‐Allenynes

“…These precursors were obtained via Claisen-Cope rearrangement of propargyl vinyl ethers derived from p-toluenesulfonic acid-catalyzed condensation of aldehydes to propargyl alcohols, as described in the literature. [6] Cycloisomerization to 2-methylene-3-vinylcyclopent-3-enol or 3-vinylcyclopent-2-enone derivatives: We found that some of the allenynes could be cycloisomerized without catalyst (Table 1). Silylated allenynes 1 a (R = SiMe 3 , Table 1, entry 1), 1 d (R = SitBuMe 2 , Table 1, entry 7), 1 e (R = SiPhMe 2 , Table 1, entry 9), 1 f (R = SiPh 3 , Table 1, entry 11), and 1 g (R = SiiPr 3 , Table 1, entry 13) were converted in high Abstract: Chemo-and stereoselective transformations of 3-hydroxy-1,5-allenynes 1 into a variety of new and potentially useful cyclic compounds have been achieved.…”

Synthesis and odour evaluation of allenic derivatives

“…Allenic aldehyde 1 (3.75 g, 54%) was obtained as a yellow oil from 2-methylbut-3-yn-2-ol (4.2 g, 49.9 mmol,) and iso-butyraldehyde (9.0 g, 124.7 mmol). 1 (14), 43 (73), 41 (97). Spectral data correspond to the literature.…”

“…Spectral data correspond to the literature. [14] 5-ethyl-2,2-dimethylhepta-3,4-dienal (2). Allenic aldehydes 2 (1.13 g, 51%) was obtained as a colourless oil 3-ethylpent-1-yn-3-ol (1.72 ml, 13.27 mmol) and iso-butyraldehyde (3.04 ml, 33.43 mmol).…”

“…Allenic acetate 13 (655 mg, 57%), was obtained as a colourless oil form allenic alcohol 8 (900 mg, 5.8 mmol). 5-cyclohexylidene-3,3-dimethylpent-4-en-2-yl acetate (14). Allenic acetate 14 (896 g, 92%), was obtained as a colourless oil form allenic alcohol 9 (800 mg, 4.1 mmol).…”

From Allenes to Cyclic Compounds by Hetero‐Ene Synthesis

“…-allenic aldehydes 7 (Scheme 5), obtained by the method of Bly and Koock [10] via a Claisen rearrangement, were converted into the homologous -y-allenic aldehydes via vinyl ether formation, by the Horner-Wittig reaction [11] . Reaction of 7 with the phosphine Reaction of allenyllithium lIe with 2.…”