Regioselectivity in the reaction of tantalum-unsymmetrical acetylene complexes with carbonyl compounds. Stereoselective preparation of 1-alkenyl sulfides, [alpha],[beta]-unsaturated esters, and amides

Journal Article · Fri Dec 04 04:00:00 EST 1992 · Journal of Organic Chemistry; (United States)

DOI:https://doi.org/10.1021/jo00051a023· OSTI ID:5933356

Kataoka, Yasutaka; Miyai, Jiro; Tezuka, Makoto; Takai, Kazuhiko; Utimoto, Kiitiro ^[1]

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1. Kyoto Univ., Yoshida (Japan)

Tantalum-alkyne complexes, derived by treatment of aklynes with low-valent tantalum (TaCl[sub 5] and zinc), react in situ with carbonyl compounds to give (E)-allylic alcohols stereoselectively. When unsymmetrical acetylenes are employed in the reaction, two regioisomeric allylic alcohols are produced. The regioselectivity of the reaction depends on the steric and electronic effects of the substituents on the acetylenes. For example, treatment of tantalum-allkyne complexes derived from methyl alkynyl sulfides with carbonyl compounds yields (E)-3-hydroxy-1-propenyl methyl sulfides in a regioselective manner. Tantalum-alkyne complexes derived from acetylenic esters react with carbonyl compounds regioselectively at the [alpha]-position of the esters to give Z-isomers of trisubstituted [alpha],[beta]-unsaturated esters. In contract, tantalum-alkyne complexes derived from acetylenic amides react with carbonyl compounds predominantly at the [beta]-position of the amides. The regioselectivity of the reaction between acytylenic amides and aldehydes, however, cannot be explained solely in terms of the steric and electronic effects of the substituents. Strong coordination of the amide group to the tantalum center could also be responsible for the observed selectivity, which is opposite to that observed with tantalum-acetylenic ester complexes. 18 refs., 1 tab.

• OSTI ID: 5933356
• Journal Information: Journal of Organic Chemistry; (United States), Journal Name: Journal of Organic Chemistry; (United States) Vol. 57:25; ISSN 0022-3263; ISSN JOCEAH
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACETYLENE
ALKYNES
AMIDES
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COMPLEXES
ESTERS
HYDROCARBONS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
STEREOCHEMISTRY
SULFIDES
SULFUR COMPOUNDS
SYNTHESIS
TANTALUM COMPLEXES
TRANSITION ELEMENT COMPLEXES