RESUMEN
The straightforward construction of stereogenic centers bearing unprotected functional groups, as in nature, has been a persistent pursuit in synthetic chemistry. Abundant applications of free enantioenriched allyl alcohol and allyl hydroxylamine motifs have made the asymmetric hydration and hydroaminoxylation of conjugated dienes from water and hydroxylamine, respectively, intriguing and efficient routes that have, however, been unachievable thus far. A fundamental challenge is the failure to realize transition-metal-catalyzed enantioselective C-O bond constructions via hydrofunctionalization of conjugated dienes. Here, we perform a comprehensive study toward the stereoselective formal hydration and hydroaminoxylation of conjugated dienes by synthesizing a set of new P,N-ligands and identifying an aryl-derived oxime as a surrogate for both water and hydroxylamine. Asymmetric hydroalkoxylation with new P,N-ligands is also elucidated. Furthermore, versatile derivatizations following hydration provide indirect but concise routes to formal hydrophenoxylation, hydrofluoroalkoxylation, and hydrocarboxylation of conjugated dienes that have been unreported thus far. Finally, a ligand-to-ligand hydrogen transfer process is proposed based on the results of preliminary mechanistic experiments.
RESUMEN
Different from electronically matched 1,4- and 1,6-additions, herein, we disclose an electronically mismatched 1,5-conjugate addition process with oximes as the nucleophiles. By this design, the oxime moieties are readily introduced to the γ-position of the electron-deficient substrates in good yields, excellent regioselectivities, and high enantioselectivities. The corresponding allyl oximes are also conveniently transformed into a series of valuable enantioenriched skeletons.
RESUMEN
The impact of the high-temperature phase change material on conventional infrared decoy's combustion performance and infrared radiation characteristics was studied. The selected high-temperature phase change materials did not reduce infrared radiation in the 3-5 microm or 8-14 microm band of infrared decoy, while extended the burning time, and reduced the burning rate of the grain, thus prolonged the effective interference time of IR decoy. The results show the phase change material is effective infrared decoy functional additives.
RESUMEN
OBJECTIVE: To study the clinicopathologic features of myeloid sarcoma and to evaluate the role of immunohistochemical study in diagnosis of this entity. METHODS: Eighty-two cases of myeloid sarcoma were retrieved from the archives of Department of Pathology, West China Hospital of Sichuan University during the period from January, 1990 to February, 2005. The morphologic features were reviewed and classified according to the 2001 WHO classification for hematopoietic and lymphoid tissue tumors. Immunohistochemical study using a panel of 11 antibodies was performed on 73 cases. The survival data were collected and analyzed by SPSS 10.0. RESULTS: The median age of patients was 35.5 years. The male-to-female ratio was 1.4:1. The sites of occurrence included lymph node (43.1%), skin (16.7%), nose (7.8%), soft tissue (7.8%) and bone (6.9%). Fifty-one cases (62.2%) represented myeloid sarcoma associated with an underlying myeloproliferative disorder and 25 cases (30.5%) represented solitary myeloid sarcoma. As for the morphology, 79 cases (96.3%) were granulocytic sarcoma, including 41 cases (51.9%) blastic type, 25 cases (31.6%) immature type and 13 cases (16.5%) differentiated type. The other 3 cases (3.7%) were monoblastic sarcoma. Immature eosinophils were found in 51 cases (64.6%) of granulocytic sarcoma, among which 13 cases (31.7%) were of blastic type. Immunohistochemical study showed that 95.9% cases (70/73) were positive for myeloperoxidase, 95.5% (63/66) for lysozyme, 95.2% (60/63) for CD68 (KP1), 90.8% (59/65) for leukocyte common antigen, 85.7% (54/63) for CD43, 77.8% (49/63) for CD117, 58.7% (37/63) for CD99, 54.0% (34/63) for CD15, 22.2% (14/63) for CD34, and 4.7% (3/64) for CD68 (PG-M1). Proliferation index, as demonstrated by Ki-67 positivity, was 0.49+/-0.22. Follow-up data was obtained in 59 of the 82 patients. The two- and five-year survival rates were 36.1% and 17.3% respectively. No significant prognostic factors were found in the survival analysis. CONCLUSIONS: Myeloid sarcoma may precede, develop in a background of myeloproliferative disorder or even after remission of the disease. The presence of immature eosinophils is an important morphologic clue and immunohistochemical study plays an essential role in arriving at a correct diagnosis. Immunopositivity for myeloperoxidase is specific for granulocytic differentiation, while CD68 (PG-M1)-positivity suggests monocytic differentiation. Detailed clinicopathologic correlation is also helpful.