Formation of beta-Allenic Alcohols in Reactions of Acetylenes with Lithium Aluminium Hydride.

Synthesis of 8-methylnonane-1,6,7-trien-4-one and related allenes as potentially useful synthetic precursors

“…The preparation reported in the present work afforded the dienol 17 in comparable yields (72%) in six steps utilizing simple reagents. However, oxidation of the allenic alcohol 17 by the chromium trioxide-pyridine complex gave the isomerized aldehyde 5-methyl-2,4-hexadienal (23) …”

“…74-76 °C/20 mmHg (lit. [23] 75 °C/20 mmHg). IR (film): selected bands at 3320 (s) OH, 2900 (s) aliphatic CH, 1960 (w) allenic C=C=C str., cm (23).…”

“…[23] 75 °C/20 mmHg). IR (film): selected bands at 3320 (s) OH, 2900 (s) aliphatic CH, 1960 (w) allenic C=C=C str., cm (23). Chromium trioxide (4 g, 40 mmol) was added portion-wise to a stirred solution of dry pyridine (6.3 g, 80 mmol) in CH 2 Cl 2 (75 mL) at room temperature (with occasional cooling in a cold water bath).…”

Pd(0)-Catalyzed Insertion−Cyclization Reaction of 2,3-Allenols with Aryl or Alkenyl Halides. Diastereoselective Synthesis of Highly Optically Active trans-2,3-Disubstituted Vinylic Oxiranes

“…In our first attempt, we synthesized 1,2-octadien-4-ol and studied its Pd(0)-catalyzed cyclization reaction with PhI under various reaction conditions (Scheme 2). Luckily and surprisingly, we observed in our first try the formation of the three-membered ring, i.e., 2-(1‘-phenylethenyl)-3-( n -butyl)oxirane 3a , under the conditions for the corresponding cyclization reaction of 1,2-allenyl carboxylic acids (Scheme 2) 3c.…”

“…Jung et al studied the rearrangement of vinylic epoxides for the synthesis of α-alkyl amino aldehydes and acids which can be easily converted to the optically active ( R )-1,2-dodecadien-4-ol ( 1b ) (Scheme ) . Its cyclization reaction with (1 E )-hexenyl iodide, p -methylphenyl iodide, and p -methoxyphenyl iodide afforded ( R , R )- 3k , ( R , R )- 3l , and ( R , R )- 3m , respectively (Scheme )…”