ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The transition-metal-carbonyl-induced cyclodimerization of 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene is strongly affected by substitution at C(1) While 5,6-dimethylidene-7-oxabicyclo[2.2.1]hept-2-ene-l-methanol (7) refused to undergo [4 + 2]-cyclodimerization in the presence of [Fe2(CO)9] in MeOH, 1-(dimethoxymethyl)-5,6-di-methylidene-7-oxabicyclo[2.2.1]hept-2-ene (8) led to the formation of a 1.7:1 mixture of ‘trans’ (19, 21, 22) vs. ‘cis’ (20, 23, 24) products of cyclodimerization together with tricarbonyl[C, 5,6, C-η-(l-(dimethoxymethyl)-5,6-di-methylidenecyclohexa-1,3-diene)]iron (25) and tricarbonyl[C,3,4, C-η-(methyl 5-(dimethoxymethyl)-3,4-di-methylidenecyclohexa-1,5-diene-l-carboxylate)]iron (26). The structures of products 19 and of its exo (21) and endo (22) [Fe(CO)3(1,3-diene)]complexes) and 20 (and of its exo (23) and endo (24) (Fe(CO)3(1,3-diene)complexes) were confirmed by X-ray diffraction studies of crystalline (1RS, 2SR, 3RS, 4RS, 4aRS, 9aSR)-tricarbonyl[C, 2,3, C-η-(1,4-epoxy-1,5-bis(dimethoxymethyl])-2,3-dimethylidene-1,2,3,4,4a,9,9a,10-octahydroanthracene)iron (21). In the latter, the Fe(CO)3(1,3-diene) moiety deviates significantly from the usual local Cs symmetry. Complex 21 corresponds to a ‘frozen equilibrium’ of rotamers with η-alkyl, η3-allyl bonding mode due to the acetal unit at the bridgehead centre C(1).
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19890720506
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