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beta-Elimination of O-acetyl 1-chloro-1-trimethylsilylalkan-2-ols 1 was achieved by using samarium diiodide as a metaling reagent and afforded the corresponding (Z)-vinylsilanes with high stereoselectivity. The starting compounds 1 were easily prepared by treatment of different aldehydes with (chlorolithiomethyl)trimethylsilane and further acetylation.
A surprising samarium diiodide-induced coupling reaction of carbonyl compounds with methoxyallene provided 4-hydroxy 1-enol ethers, which are versatile synthetic building blocks. In this coupling reaction, methoxyallene serves as an acrolein equivalent, which cannot directly be employed. [reaction: see text]
Gamma,delta-unsaturated ketones undergo two very different stereoselective cyclization reactions mediated by samarium(II) iodide depending upon the alcohol cosolvent used in the reaction. Switching between an unprecedented aldol spirocyclization and a novel cyclobutanol-forming process can be achieved simply by changing the alcohol cosolvent from methanol to tert-butyl alcohol. [reaction: see text]
[reaction: see text] Samarium diiodide promotes smooth reductive cyclizations of gamma-naphthyl-substituted ketones to afford tri- and tetracyclic compounds in high yields and with excellent stereoselectivities. Cyclic ketones furnish steroid-like compounds with "unnatural" cis/cis annulation of rings B/C/D. The remaining styrene-type double bond of ring B allows further stereoselective reactions. Cases with matched and mismatched relative configuration could be identified leading to dramatic differences in the ring closure ability.
[reaction: see text] We synthesized a chiral multidentate ligand, (R,R,R,R)-N,N,N',N'-tetra(2-hydroxy-2-phenylethyl)-1,3-xylylene diamine [(R)-2], which can support two metals at adjacent positions. Asymmetric transfer hydrogenation of acetophenone and its derivatives was conducted by using salt-free bimetallic lanthanoid complexes of (R)-2, and the combination of two samarium atoms and (R)-2 was found to be the best catalyst system for asymmetric transfer hydrogenation of aryl ketones in high enantioselectivity (up to >99% ee).
A complex of samarium diiodide (SmI(2)) with tetraglyme catalyzes the intermolecular pinacol coupling of aromatic or aliphatic aldehydes at loadings of 10 mol % in the presence of Me(2)SiCl(2) and Mg. Diastereoselectivity of up to 95/5 (+/-/meso) has been achieved for aliphatic aldehydes and up to 19/81 (+/-/meso) for aromatic aldehydes. De values of up to 99% have been achieved in intramolecular pinacol coupling reactions using the SmI(2)/tetraglyme/Mg/Me(2)SiCl(2) catalytic system.
[reaction: see text] A series of [n]paracyclophanediols (n = 8-12) was synthesized by samarium-catalyzed pinacol coupling for their ansa-bridge formation. Enantiomerically pure [n]paracyclophane esters were derived from the diols in a several steps via chiral resolution (for n = 10) or via crystallization-induced asymmetric transformation (for n = 11) by using amino alcohol auxiliaries and their selective cleavages.
[reaction: see text] The photoinduced metalation of nonactivated C-Cl bonds of O-acetyl chlorohydrins is promoted by samarium diiodide. As a result of this, beta-elimination of O-acetyl chlorohydrins is achieved, affording the corresponding (Z)-alkenes with total or high stereoselectivity.
The different degrees of freedom of a given system are usually independent of each other but can in some materials be strongly coupled, giving rise to phase equilibria sensitively susceptible to external perturbations. Such systems often exhibit unusual physical properties that are difficult to treat theoretically, as exemplified by strongly correlated electron systems such as intermediate-valence rare-earth heavy fermions and Kondo insulators, colossal magnetoresistive manganites and high-transition temperature (high-T(c)) copper oxide superconductors. Metal fulleride salts-metal intercalation compounds of C60--and materials based on rare-earth metals also exhibit strong electronic correlations. Rare-earth fullerides thus constitute a particularly intriguing system--they contain highly correlated cation (rare-earth) and anion (C60) sublattices. Here we show, using high-resolution synchrotron X-ray diffraction and magnetic susceptibility measurements, that cooling the rare-earth fulleride Sm2.75C60 induces an isosymmetric phase transition near 32 K, accompanied by a dramatic isotropic volume increase and a samarium valence transition from (2 + epsilon) + to nearly 2 +. The negative thermal expansion--heating from 4.2 to 32 K leads to contraction rather than expansion--occurs at a rate about 40 times larger than in ternary metal oxides typically exhibiting such behaviour. We attribute the large negative thermal expansion, unprecedented in fullerene or other molecular systems, to a quasi-continuous valence transition from Sm(2+) towards the smaller Sm((2+epsilon)+), analogous to the valence or configuration transitions encountered in intermediate-valence Kondo insulators like SmS (ref. 3).
The first samarium(II)-mediated spirocyclisation onto an aromatic ring was achieved by the reaction of methyl 4-(4-oxoalkyl)benzoates with SmI2 in the presence of i-PrOH and HMPA, yielding methyl 1-alkyl-1-hydroxyspiro-[4.5]dec-6-ene-8-carboxylates in moderate to high yields.
A new linker for the solid phase synthesis of functionalised carbonyl compounds which is cleaved under mild, neutral conditions using samarium(II) iodide has been developed; the manipulation of an immobilised gamma-butyrolactone has been carried out to illustrate the utility of the linker.
Treatment of the THF solution of (MeC5H4)2Sm(THF) with an equivalent of carbodiimine [RN=C=NR](R = Pr(i) or Cy; Cy = cyclohexyl) in the presence of an equivalent of hexamethylphosphoric triamide (HMPA) at room temperature gives, via a reduction-coupling reaction of carbodiimine, the corresponding bimetallic oxalamidino complex of samarium [eta4-C2(NR)4][(MeC5H4)2Sm(HMPA)]2.2THF.
The first divalent samarium bis(amidinate) has been prepared and aspects of its novel chemistry, including the preparation of a sterically hindered homoleptic Sm(III) tris(amidinate), explored.
[(C5Me5)2Sm(mu-O2CPh)]2 reacts with iBu3Al to form a mixed bridge samarium aluminium complex [(C5Me5)2Sm(mu-O2CPh)(mu-iBu)Al(iBu)2], that displays two different carboxylate orientations toward the metals in a single crystal.
OBJECTIVE: To assess the therapeutic efficacy and toxicity of samarium-153-ethylenediaminetetramethylene phosphonic acid ((153)Sm-EDTMP) and pamidronate disodium in patients with painful metastatic bone cancer. SUBJECTS AND METHODS: Eighteen patients with histopathologically confirmed malignancy and multifocal bone metastases were randomized into two equal groups of 9 patients each. Group A was treated with (153)Sm-EDTMP, while group B was treated with pamidronate disodium. The pain score for each patient was recorded before and after therapy using visual analogue scales that graded both the intensity and frequency of the bone pain. Therapeutic response was classified as inefficient, mild, effective and excellent. RESULTS: Pain score in each group prior to therapy was more than 6. In group A, 2 (22.2%) and 7 (77.8%) cases showed mild and effective response, respectively. The therapeutic efficacy of (153)Sm-EDTMP was adjudged to be 77.8%. Transient myelosuppression was generally mild and reversible with white blood cells and platelets recovering after 6 weeks. In group B, palliative response in 4 cases (44.4%) was inefficient, in 1 case (11.1%) mild, in 3 cases (33.3%) effective and in 1 case (11.1%) excellent, with a therapeutic efficacy of 44.4% for pamidronate disodium. No hematological toxicity was noted. CONCLUSION: The data showed that the therapeutic efficacy of (153)Sm-EDTPM was higher than that of pamidronate disodium (for pain relief maintained more than 3 weeks) and its incidence of blood toxicity was also higher than that of pamidronate disodium.
PURPOSE: To evaluate the effectiveness and safety of samarium-153 (153Sm) lexidronam (EDTMP) in a double-blind, placebo-controlled study. PATIENTS AND METHODS: Patients with painful bone metastases secondary to a variety of primary malignancies were randomized to receive 153Sm-EDTMP 0.5 or 1.0 mCi/kg, or placebo. Treatment was unblinded for patients who did not respond by week 4, with those who had received placebo eligible to receive 1.0 mCi/kg of active drug in an open-label manner. Patient and physician evaluations were used to assess pain relief, as was concurrent change in opioid analgesia. RESULTS: One hundred eighteen patients were enrolled onto the study. Patients who received 1.0 mCi/kg of active drug had significant reductions in pain during each of the first 4 weeks in both patient-rated and physician-rated evaluations. Pain relief was observed in 62% to 72% of those who received the 1.O-mCi/kg dose during the first 4 weeks, with marked or complete relief noted in 31% by week 4. Persistence of pain relief was seen through week 16 in 43% of patients who received 1.0 mCi/kg, of active drug. A significant correlation (P = .01) was observed between reductions in opioid analgesic use and pain scores only for those patients who received 1.0 mCi/kg 153Sm-EDTMP. Bone marrow suppression was mild, reversible, and not associated with grade 4 toxicity. CONCLUSION: A single dose of 1.0 mCi/kg of 153Sm-EDTMP provided relief from pain associated with bone metastases. Pain relief was observed within 1 week of administration and persisted until at least week 16 in the majority of patients who responded.
CONTEXT: More than 50% of patients with prostate, breast or lung cancer will develop painful bone metastases. The purpose of treating bone metastases is to relieve pain, reduce the use of steroids and to maintain motion. OBJECTIVE: To evaluate the use of samarium-153-EDTMP (153Sm-EDTMP) for the treatment of bone pain secondary to metastases that is refractory to clinical management. TYPE OF STUDY: Retrospective. SETTING: Division of Nuclear Medicine, Universidade Estadual de Campinas (Unicamp). METHODS: Fifty-eight patients were studied (34 males) with mean age 62 years; 31 patients had prostate cancer, 20 had breast cancer, three had lung cancer, one had lung hemangioendothelioma, one had parathyroid adenocarcinoma, one had osteosarcoma and one had an unknown primary tumor. All patients had multiple bone metastases demonstrated by bone scintigraphy using 99mTc-MDP,and were treated with 153Sm-EDTMP. Response to treatment was graded as good (pain reduction of 50-100%), intermediate (25-49%) and poor (0-24%). RESULTS: All patients showed good uptake of 153Sm-EDTMP by bone metastases. Among the patients with prostate cancer, intermediate or good response to therapy occurred in 80.6% (25 patients) and poor response in 19.4% (6). Among the patients with breast cancer, 85% (17) showed intermediate or good response to therapy while 15% (3) showed poor response. All three patients with lung cancer showed poor response to treatment. The lung hemangioendothelioma and unknown primary lesion patients showed intermediate response to treatment; the osteosarcoma and parathyroid adenocarcinoma patients showed good response to treatment. No significant myelotoxicity occurred. DISCUSSION: Pain control is important for improving the quality of life of patients with advanced cancers. The mechanism by which pain is relieved with the use of radionuclides is still not yet completely understood, however, the treatment is simple and provides a low risk of mielotoxicity. CONCLUSION: Treatment with 153Sm-EDTMP can control the pain secondary to bone metastases effectively in most patients with breast and prostate cancer without significant side effects.
BACKGROUND: Systemic therapy with radionuclides may be used for the treatment of patients with painful skeletal metastases owing to its efficacy, low cost and low toxicity. Imported radionuclides for pain palliation, like Strontium-89 are expensive; particularly for developing countries. In the Indian scenario, Samarium-153 (Sm-153) is produced in our own reactors and as a result, it is readily available and economical. AIM: We undertook this study to determine the efficacy and toxicity of single-dose Sm-153 ethylenediamine tetramethylene phosphonate as a palliative treatment for painful skeletal metastases. MATERIALS AND METHODS: Eightysix patients with painful skeletal metastases from various primaries, were treated with Sm-153 EDTMP at a dose of 37 MBq/kg. The effects were evaluated according to change in visual analogue pain score, analgesic consumption, Karnofsky performance score, mobility score and blood count tests, conducted regularly for 16 weeks. STATISTICS: Repeated measures analysis. RESULTS: The overall response rates were 73%, while complete response was seen in 12.4%. Reduction in analgesic consumption with improvement in Karnofsky performance score and mobility score, was seen in all responders. Response rates were 80.3 and 80.5% in breast and prostate cancer, respectively. One case, each of Wilms tumor, ovarian cancer, germ cell tumor testis, multiple myeloma, primitive neuroectodermal tumor and oesophageal cancer, did not respond to therapy. No serious side-effects were noted, except for fall in white blood cell, platelet and haemoglobin counts, which gradually returned to normal levels by six-eight weeks. CONCLUSION: Sm-153 EDTMP provided effective palliation in 73% patients with painful bone metastases: the major toxicity was temporary myelosuppression.