Photoreactions of a methylene-spirane and dispirane with Fe(CO)₅. σ,π-Complex formation from a double cyclopropane rearrangement

Abstract

The major product from the photoreaction of 4-methylenedispiro[2,1,2,3]decane (5) with Fe(CO), is shown to be a tricarbonyliron a,n-complex of structure (7), whereas the products from Pmethylenespiro[2,4]heptane (9) and 4-methylenespiro [2, Bloctane (15) are the respective bi-cyclic enones (12)-(13) and (16). OUR study of the thermolysis' and photolysis3 of vinylcyclopropenes in the presence of Fe(CO), has indicated that the small ring may be cleaved via two distinctly different reactions; (a) the Fe(CO),-induced metal insertion into a CH, + Fe(COI, (31 strained o-bond coupled with hydrogen migration to provide diene-Fe(CO), n-complexes [(l) + (2)]; (b) thephoto-induced cycloinsertion of carbon monoxide across the 'homodienic system' to yield cyc1ohexenones.i The only example in which these two reactions take place con-currently is that of 1, 1-dicyclopropylethylene (1), which on on thermolysis with Fe(CO), gives rise to a 1 : 1-mixture of (2) and (4)Ibs4 and on photolysis yields predominantly the cyclohexenone (4) product. Since the n-complex (2) is inert

Reactions of Tricyclic Vinylcyclopropanes with Metal Carbonyls

“…spectrum (C6D6)3) exhibited signals of an olefinic proton at an uncomplexed double bond at 6 4,76 (dx m, J(7,8)= 8.0, H-C (7)), two protons of a n-allylic system bonded to iron at 6 3.98 (d, J(3,2) = 7.0, H-C (3)) and 3.40 (dxd, J(2,3)=7.0, H-C(2)), three methyl groups at 6 1.85 (s, H3C-C(4)), 1,64 (small m, H3C-C(6)) and 1.08 (s, H3C-C(1)), and a proton at a bridgehead carbon atom bonded to iron at 6 0.86 (m, H-C(9)). This high field chemical shift of H-C(9) is in agreement with other observations [3] [6]. The mass spectrum of complex 8 showed a molecular ion peak at m/e 3 14 and the characteristic fragmentation pattern (mle 286 ( M + -CO, 36), 258 (M' -2C0, 59) and 230 ( M + -3 C 0 , 100)).…”

“…-Vinylcyclopropanes are known to react with iron carbonyls to give iron complexes resulting from cleavage of a C-C bond of the cyclopropane ring [l] [2]. This type of complex formation was also observed in the reactions of I) Deceased December 19, 1976 bicyclic [3] [4] and polycyclic hydrocarbons containing vinylcyclopropane systems such as bullvalene [5 a], isobullvalene [5 c], semibullvalene [6], homosemibullvalene [7], tetracyclo [4.4.0.05~7.02~'0]deca-3,8-diene [5 b], azabullvalene [8], and barbaralone [9]. The reaction was extended to the hetero analogues (e.g., vinyloxiranes [ 101 [ 111 and vinylaziridine [ lOa]), in which a C-X bond was cleaved to form iron complexes.…”

Metal-induced rearrangements and insertions into cyclopropyl olefins

“…The latter could be induced by Fe(CO)5 to rearrange to the diene tt complex (27) but not to , -allyl complex (25). 24 The striking chemical stability of 25 resembles very closely that of the , -allyl complexes resulting from In contrast to 28-33 in which the bridgehead hydrogens are structurally precluded from undergoing a shift because this would lead to anti-Bredt bridgehead olefins, there is no obvious reason why the , -allyl complex 25 could not be induced to rearrange into the diene tt complex 27. The , -allyl complex from the parent vinylcyclopropane (34, R = H) was reported to collapse readily into the respective isomers of 1,3pentadiene tt complex (5h, R = H).30…”

Regio- and stereospecific acyl-metal insertion from pentacarbonyliron-mediated photolysis of (+)-.alpha.-thujene

“…H Unlike bicyclo[3.1.0]hex-2-ene, the photochemical reaction of 4-methylenespiro[2.x]alkanes provides bicyclic enones in very good yields (eq 5). 6 We report here the results of a study in which (+)-a--thujene (I) was exposed to the action of Fe(CO)s under photolytic conditions similar to those of the earlier studies and also to Fe3(CO)i2 under thermal conditions.…”

“…Compounds 5, 6, and 7 were prepared similarly from tribenzyltin chloride and the corresponding methyl, cyclopentyl, and phenyl Grignard reagents in diethyl ether and were purified by column chromatography (Si02 or 1202) using benzene as the eluent. Compound 5 (mp 47-49 °C) had a NMR spectrum (270 MHz, CCI4, Me4Si) with signals at 0.15 (CHuSn), 2.55 (CH2Sn), and 6.80 and 7.46 ppm (aromatic) in the correct ratios; compound 6 (mp 66-69 °C; MeOH) had signals (60 MHz) at 1.1-1.8 (ring CH2's), 2.20 (CH2Sn), and 6.63 and 7.23 ppm (aromatic); compound 7 (thick oil) had signals (60 MHz) at 2.34 (CH2Sn) and 6.63 and 7.20 ppm (aromatic). Compound 9 was prepared by the following procedure: diphenylethylmethyltin was reacted with hydrochloric acid in methanol to give phenylethylmethyltin chloride.…”