(7-Phenyl-7-phosphadispiro[2.0.2.1]heptane)pentacarbonyltungsten (8), a phospha[3]triangulane, was synthesized from bicyclopropylidene. Its single-crystal X-ray structure determination is reported. Comparison of the crystal structure data with those of the related phosphaspiropentane 7 and phosphirane 6 complexes suggests that the phosphirane ring tightens when the number of spiro atoms is increased. This is supported by the B3LYP and MP2/6-31G* computed geometries of the uncomplexed parent systems. Ab initio calculated heats of formation and strain energies (SE) are reported for the parent phosphirane 11, phosphaspiropentane 12, and phospha[3]triangulane 13 using both G2MP2 theory and ring separation reactions. Our best estimates for the ΔH f of 11, 12, and 13 are 18.3, 48.4, and 78.2 kcal/mol, respectively, with corresponding SE values of 21.3, 54.7, and 87.9 kcal/mol. For comparison, the slightly modified G2MP2 method was also applied to cyclopropane 1, spiropentane 2, and [3]triangulane 3 to give respective ΔH f values of 12.6, 44.3, and 75.3 kcal/mol, with corresponding SEs of 28.0, 64.6, and 100.5 kcal/mol, all of which are in excellent agreement with reported experimental data. These strain energies suggest that the excess strain per spiro atom is 5.3 kcal/mol for phospha[n]triangulanes, which is smaller than the 8.6 kcal/mol determined from the heat of combustion measurements for the [n]triangulanes.

76 ±4 Gy Vs 113±25 Gy & 86 ±14 Gy). D 90 did not correlate with point A dose (p = 0.78). Four percent of the patients (1/25) had acute Grade 3 GI toxicity; none had acute GU toxicity. A total of 4% of patients (1/25) had chronic Grade 3 GI toxicity; none had chronic GU toxicity. OS and DFS at 1 year were 100% and 94.4%. Four percent of the patients (1/25) failed locally and 4% failed distally (1/25). The patient who failed locally received 76 Gy to point A (adenocarcinoma histology). Conclusions: Image guided cervix BT has changed the paradigm for target definition and dose evaluation, but clinical practice of dose prescription itself remains varied as documented in practice patterns. As observed in this study, prescribing to point A may result in higher OAR doses and reduced target coverage. This data indicates that point A as a surrogate for target definition in an era of image guided brachytherapy might be unnecessary, and possibly detrimental.

Three stable alkylidenephosphiranes have been synthesized from the addition of the terminal phosphinidene complex Ph-P-W(CO) 5 to allene, 1,1-dimethylallene, and tetramethylallene. Isopropylidenephosphirane 16b was characterized by a single-crystal X-ray structure determination. Demetalation of its W(CO) 5 group provides the uncomplexed compound. The addition reaction with tetramethylallene also yields vinylphosphirane epimers, which rearrange to phospholene 20. Ab initio MP2/6-31G* structures and energies are presented for the parent uncomplexed methylenephosphirane and its dimethyl derivatives.Ring strain augmented by the presence of an exocyclic double bond makes the heteroatom analogues of methylenecyclopropanes (1) fascinating compounds. 1,2 Strain underlies, for example, the biradical interconversion of the valence isomers 2 and 3, which consequently have received particular attention. [3][4][5] While synthesizing such systems is inherently challenging, their presence as reactive and versatile intermediates has been well established. Expectantly, the stability of the methylene derivatives of the aziridines, oxiranes, and thiiranes increases with bulky substituents on the heteroatom, ring, and/or double bond. These sterically congested systems are typically generated via ring closure reactions, either thermally or photochemically induced, rather then by, e.g., the epoxidation of or the nitrene addition to allenes. 1,6 Our interest in these heterocycles and their even more strained higher homologues, the radialenes 4, 7 arose because of the noticeable elusive phosphorus analogues. 8Only recently did Yoshifuji et al. 9 report the first synthesis of a congested methylenephosphirane, 5, via the addition of dichlorocarbene to a sterically protected 1-phosphaallene (eq 1). No structural details were provided. Subsequently, Manz and Maas 10 reported two similarly congested methylenephosphiranes 6a,b. These stable compounds were obtained from thermal N 2 -extrusion of diazaphosphole precursors, thereby extending the method explored in detail by Quast and coworkers 11 for the syntheses of the O-, S-, and N-analogues. Product formation is presumed to occur via ring closure of the reactive 2-phosphacumulene intermediates (eq 2). The yields are modest due to competing biradical H-abstractions. The difference between the ab initio geometry of the parent methylenephosphirane, C 3 H 5 P (7), 12 and the single-crystal X-ray structure of 6a emphasizes the effect of steric crowding (see also later). 10 These two synthetic routes are, however, rather limited in scope due to the high sensitivity of phosphaallene and 2-phosphacumulenes. 8 A third route has been attempted, Penn, R. E.; Ennis, M. D.; Owens, T. A.; Yu, S. L. J. Am. Chem. Soc. 1978, 100, 7436. Jongejan, E.; Buys, Th. S. V.; Steinberg, H.; de Boer, Th. Behr, H.; Adiwidjaja, G.; Tangerman, A.; Lammerink, B. H. M.; Zwanenburg, B.

The quaternary TV-allyl bromide salt 5 of allyl a-[2-(5-azaadamantylidene)]benzyl ether upon warming gave the Claisen rearrangement products 6 is the ratio E/Z = 93:7. The epoxidation of the V-oxide 8 of 2-methylene-5-azaadamantane 7 with m-CPBA gives rise to the two diastereomeric epoxides 9 in the ratio E/Z = 19:81. Reaction of the methyl iodide salt of this olefin with bromine in water produces the Eand Z-dibromides 10 in the ratio 74:26 as well as the corresponding glycols 12 in the ratio 86:14. The same reaction in methanol gives the Eand Z-isomers of 10 alone, in the ratio of 35:65. The interpretation is that, in all of these reactions, the trigonal carbon preferably undergoes addition at that face which is antiperiplanar to the more electron-rich vicinal bonds, and does so by margins substantially in excess of those observed with the corresponding 5-fluoroadamantanes. This fact lends further strength to our previously drawn conclusion that hyperconjugative transition state stabilization is the principal factor in the electronic component of face selection.

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