ISSN:
0009-2940
Keywords:
Bicyclic manganese compounds
;
P-P bonds
;
Activated alkynes
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The product pattern of the reaction of the alkynes ZC≡CZ (4-11) [Z = CO2R: R = Me (4), Et (5), nPr (6), iPr (7), nBu (8), nPent (9), neo-Pent (10), cyc-Hex (11)] with the diphospha-manganacyclopropanes (1-3) depends on the polarity of the employed solvent. Whereas in n-hexane the diphosphamanganabicyclo[3.3.0]octadienones 12a-q, the diphosphamanganacyclopentenes 13a-h, and the triphosphamanganabicyclo[3.2.0]heptenones 14a-h are formed, in THF only the five-membered heterocycles 13 occur. Compound 14d is easily oxidized to the corresponding oxide 15d. According to X-ray structural analyses, both 14d and 15d crystallize in the space group P&1macr;. The Lewis basic properties of the phosphorus atom P2 in the heterocycle 1 were corroborated by reaction of 1 with THFCr(CO)5 leading to the adduct (16). Quantitative 31P{1H}-NMR investigations in CDCl3 enable the determination of the product ratio 13/12 as a function of the steric encumbrance of the ester substituents. An increase of the steric hindrance leads to the preferential formation of the mo-nocyclic compounds 13. If the steric demand at the phosphorus atom P2 is released, only the bicyclic compounds 12i-q are formed.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19961290212
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