Improved synthesis of dichloromethylenetriphenylphosphorane

Clement, Bradford M.; Soulen, Robert L.

doi:10.1021/jo00865a032

Cited by 24 publications

(17 citation statements)

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“…Unfortunately, under the reaction conditions only one isomer 4d could be isolated. The preferential formation of cis-8iert-butyl-3-methylene-l-oxaspiro [4.5]decan-2-one rather than the trans isomer has been reported.3b From this fact and the NMR data as well as our observation of the preferential crystallization of 4c (as evidenced by the X-ray diffraction analysis given later in the paper), we tentatively assign the C(4)-0(7) bond as axial in 2,6-diphenyl-9methylene-7-oxa-l-thiaspiro [4,5]decan-8-one (4d).…”

Section: Resultssupporting

confidence: 56%

“…= 3«^h(6J,h(5J = 11-0 Hz and 3«/h(2JH(3J = 3JH(6j,H(5j = 4.0 Hz (which are typical values expected for vicinal coupling constants Vtrane and Vcis in the chair conformation for a cyclohexane system7), indicate that the C(2)-H and C(6)-H bonds are axial. The signals due to the H(3) and H(5) in 4d (or 5d) at 2.04-2.41 (m, 4 H) are considerably downfield from the signal of similar protons in 4c (^Sc) at 1.59-2.09 and suggest that H(3) and H (5) in 4d (or 5d) are situated toward an edge of the arene ring.8 A molecular model of 4d suggests that H(3) and H( 5) are indeed at the periphery of the benzene ring. The NMR spectrum of 4d also shows that the diagmagnetic anisotropy effect of the benzene ring may be felt, although to a smaller extent, even by the distant H(10) (6 2.84) in comparison to ~2.70 found for related protons in lactones 4a-c.…”

Section: Resultsmentioning

confidence: 96%

“…as a crystalline solid suggests that it was the conformer with lower lattice packing energy. Although the preference for an axial C-0 bond over an equatorial C-0 bond has been illustrated in 3-methylene-1-oxaspiro [4,5] decan-2one,3b by preferential crystallization of either 4c or 5c could not be predicted on the basis of the steric requirements of the axial methyl groups at C(2) and C(6). In order to establish the conformation of this compound in an unequivocal fashion, we performed an X-ray diffraction analysis on a single crystal of 2,2,6,6-tetramethyl-9methylene-7-oxa-l-thiaspiro [4,5]decan-8-one (4c).…”

Section: Resultsmentioning

confidence: 96%

“…In solution, 2,2,6,6-tetramethyl-9-methylene-7-oxa-lthiaspiro [4,5]decan-8-one presumably exists as an equilibrium mixture of 4c and 5c. Isolation of one conformer…”

Section: Resultsmentioning

confidence: 99%

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Synthesis and stereochemistry of thiaspiro-.alpha.-methylene-.gamma.-butyrolactones. Single-crystal x-ray diffraction analysis of 2,2,6,6-tetramethyl-9-methylene-7-oxa-1-thiaspiro[4.5]decan-8-one

Pantaleo¹,

Satyamurthy²,

Ramarajan³

et al. 1981

J. Org. Chem.

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a-Methylene-7-butyrolactone systems attached to heterocycles are rare. We reported the synthesis of a few 9-methylene-7-oxa-l-thiaspiro[4.5]decan-8-ones via a Reformatsky-type reaction on substituted 4-thianones. All products were characterized by and 13C NMR analysis as well as by mass and infrared spectra and elemental analyses. Downfield shifts for C(2,6) in 2,2,6,6-tetramethyl-9-methylene-7-oxa-l-thiaspiro[4.5]decan-8-one in the 13C NMR spectrum were of such magnitude, compared to model cyclohexyl systems, that the thianone ring was suggested to be flattened near the sulfur end of the molecule. The structure of solid 2,2,6,6-tetramethyl-9-methylene-7-oxa-l-thiaspiro[4.5]decan-8-one was established by means of an X-ray diffraction analysis of a single crystal and confirmed such a flattening. The molecule crystallizes in the space group P2i/c with unit cell parameters of a = 6.189 (3) Á, b = 11.244 (4) A, c = 18.960 (9) A, and ß = 92.39 (4)°. The structure was solved by direct methods and refined by least-squares methods to an R value of 0.057 for 2515 reflections. The five-membered lactone ring is in a flattened twist (C2) conformation, and the C-0 bond has an axial orientation at the 4-position of the thiane ring system.The diverse biological activities of the compounds having documented.1 The possible utilization of these lactones the a-methylene-^-butyrolactone moiety have been wellas antitumor agents has attracted the attention of many

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Section: Resultssupporting

confidence: 56%

Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 96%

“…In solution, 2,2,6,6-tetramethyl-9-methylene-7-oxa-lthiaspiro [4,5]decan-8-one presumably exists as an equilibrium mixture of 4c and 5c. Isolation of one conformer…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Synthesis and stereochemistry of thiaspiro-.alpha.-methylene-.gamma.-butyrolactones. Single-crystal x-ray diffraction analysis of 2,2,6,6-tetramethyl-9-methylene-7-oxa-1-thiaspiro[4.5]decan-8-one

Pantaleo¹,

Satyamurthy²,

Ramarajan³

et al. 1981

J. Org. Chem.

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“…Initial experiments of Clement and Soulen had shown that reaction of acyl cyanides with the combination BrCCl 3 -PPh 3 leads to the corresponding 3,3-dichloroacrylonitriles at lower temperatures and in higher yields than with the reaction system CCl 4 -PPh 3 . 11 These results have been taken up recently by the group of Lautens, 12 who could show that benzaldehydes and acetophenones could be converted into the dichloromethylenated products with ease. They also showed that benzyl alcohols and cinnamyl alcohol can be chlorinated with BrCCl 3 -PPh 3 .…”

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confidence: 84%