Baker's yeast mediated reduction of acenaphthenequinone within 4-10 h afforded mono-hydroxyacenaphthenone mainly with low enantioselectivity, the substrate and mono-hydroxyacenaphthenone product almost converted t...Baker's yeast mediated reduction of acenaphthenequinone within 4-10 h afforded mono-hydroxyacenaphthenone mainly with low enantioselectivity, the substrate and mono-hydroxyacenaphthenone product almost converted to dihydroxyacenaphthene after 48 h. By control of the reaction time and in the presence of DMF as co-solvent, the reduction of 6-substituted acenaphthenequinones under vigorous agitation afforded the corresponding 2-hydroxyacenaphthenones in 24-84% yields with 10-93% ee.展开更多
Coordination polymerization of renewable β-ocimene has been investigated using asymmetric diiminophosphinate lutetium complex1, β-diketiminate yttrium complex 2, bis(phosphino)carbazolide yttrium complex 3, half-san...Coordination polymerization of renewable β-ocimene has been investigated using asymmetric diiminophosphinate lutetium complex1, β-diketiminate yttrium complex 2, bis(phosphino)carbazolide yttrium complex 3, half-sandwich benzyl fluorenyl scandium complex 4 and pyridyl-methylene-fluorenyl rare-metal complexes 5a–5c. Complexes 1, 4 and 5a–5c show trans-1,2-regioselectivities and high activities, of which 5c exhibits excellent isoselectivity(mmmm>99%). Conversely, complexes 2 and 3 promote β-ocimene polymerization to produce isotactic cis-1,4-polyocimenes(cis-1,4>99%, mm>95%). Diblock copolymers cis-1,4-PIP-block-cis-1,4-POc and cis-1,4-PBD-block-cis-1,4-POc are obtained in one-pot reactions of β-ocimene with isoprene and butadiene using complex 3. Epoxidation and hydroxylation of polyocimene afford functionalized polyolefins with enhanced T_(g)(from-20 ℃ to 79 ℃ and 74 ℃) and hydrophilicity.展开更多
Lymphatic malformation (ML), formerly called cystic lymphangioma is a benign hamartomatous tumor of lymphatic vessels. The onset of lymphangiomas is either at birth (60% to 70%) or up to two years of age (90%) and rar...Lymphatic malformation (ML), formerly called cystic lymphangioma is a benign hamartomatous tumor of lymphatic vessels. The onset of lymphangiomas is either at birth (60% to 70%) or up to two years of age (90%) and rare in adults. These malformations can occur in any region of the body, Lymphangiomas have marked predilection for the head and neck region (50% - 70%). The most common location in the mouth is the dorsum of tongue. If the positive diagnosis is generally easy, the therapeutic management remains controversial. We report the clinical case of a 23-year-old adult patient with cystic lymphangioma on the floor of the oral cavity extending gradually to the right submandibular region. The clinically suspected tumor was thoroughly explored using tomodensitometry. The treatment consisted of complete resection by a cervicotomy with histological examination confirming the macroscopic diagnosis of cystic lymphangioma. Follow-up at 3 years showed no recurrence.展开更多
Lady Regio牌厕用卫生纸在投放市场不到一年的时间里，就被公认为墨西哥质量最好的卫生纸品牌。Copamex公司个人消费用卫生纸部门经理Juan Manuel Rojas先生对此解释道，“我们花大力气对市场和产品适用群体进行了研究，这一努力帮我们...Lady Regio牌厕用卫生纸在投放市场不到一年的时间里，就被公认为墨西哥质量最好的卫生纸品牌。Copamex公司个人消费用卫生纸部门经理Juan Manuel Rojas先生对此解释道，“我们花大力气对市场和产品适用群体进行了研究，这一努力帮我们开发出了新的卫生纸产品，使墨西哥的消费者有了更多的选择范围。”据Rojas说，公司主要的策略是满足重要市场的特殊需求。展开更多
A β-（1→）6）-branched β-（1→）3）-linked glucohexaose （1） and its lauryl glycoside （2）, present in many biologically active polysaccharides from traditional herbal medicines such as Ganoderma lucidum, Schizop...A β-（1→）6）-branched β-（1→）3）-linked glucohexaose （1） and its lauryl glycoside （2）, present in many biologically active polysaccharides from traditional herbal medicines such as Ganoderma lucidum, Schizophyllum commune and Lentinus edodes, were highly efficiently synthesized. Coupling of 2,3,4,6-tetra-O-benzoyl-β-D-glucopyranosyl- （1--）3）-2-O-benzoyl-4,6-O-benzylidene-a-D-glucopyranosyl trichloroacetimidate （7） with 3,6-branched acceptors 8 and 12 gave β-（1→）3）-linked pentasaccharides （9） and （13）, then via simple chemical transformation 4＇,6＇-OH pentasaccharide acceptors 10 and 14 were obtained. Regio- and stereoselective coupling of 3 with 10 and 14 gave β-（1→）3）-linked hexasaccharides （11） and （15） as the major products. Deprotection of 11 and 15 provided the target sugar 1 and 2. Thus, a new method for the preparation of this kind of compounds was developed.展开更多
A regio- and stereo-selective reduction of diketo-n-butylphosphonates by baker's yeast was reported. The chemical yield and ee value of these reactions are highly dependent on the structure of substrates. The re...A regio- and stereo-selective reduction of diketo-n-butylphosphonates by baker's yeast was reported. The chemical yield and ee value of these reactions are highly dependent on the structure of substrates. The resulting optical active hydroxy^alkanephosphonates can be used as chirons for the synthesis of polyfunctional organophosphorus compounds. As useful building block, a series of α,β-unsaturated ketones bearing chiral hydroxy group in addition to trifluoromethyl moiety was prepared via the Horner-Wadsworth-Emmons (HWE) reaction of the biotransformation products.展开更多
文摘Baker's yeast mediated reduction of acenaphthenequinone within 4-10 h afforded mono-hydroxyacenaphthenone mainly with low enantioselectivity, the substrate and mono-hydroxyacenaphthenone product almost converted to dihydroxyacenaphthene after 48 h. By control of the reaction time and in the presence of DMF as co-solvent, the reduction of 6-substituted acenaphthenequinones under vigorous agitation afforded the corresponding 2-hydroxyacenaphthenones in 24-84% yields with 10-93% ee.
基金financially supported by the open research fund program of Science and Technology on Aerospace Chemical Power Laboratory (No. STACPL120221B03)the National Natural Science Foundation of China (Nos. s22175059,52073275 and U21A20279)。
文摘Coordination polymerization of renewable β-ocimene has been investigated using asymmetric diiminophosphinate lutetium complex1, β-diketiminate yttrium complex 2, bis(phosphino)carbazolide yttrium complex 3, half-sandwich benzyl fluorenyl scandium complex 4 and pyridyl-methylene-fluorenyl rare-metal complexes 5a–5c. Complexes 1, 4 and 5a–5c show trans-1,2-regioselectivities and high activities, of which 5c exhibits excellent isoselectivity(mmmm>99%). Conversely, complexes 2 and 3 promote β-ocimene polymerization to produce isotactic cis-1,4-polyocimenes(cis-1,4>99%, mm>95%). Diblock copolymers cis-1,4-PIP-block-cis-1,4-POc and cis-1,4-PBD-block-cis-1,4-POc are obtained in one-pot reactions of β-ocimene with isoprene and butadiene using complex 3. Epoxidation and hydroxylation of polyocimene afford functionalized polyolefins with enhanced T_(g)(from-20 ℃ to 79 ℃ and 74 ℃) and hydrophilicity.
文摘Lymphatic malformation (ML), formerly called cystic lymphangioma is a benign hamartomatous tumor of lymphatic vessels. The onset of lymphangiomas is either at birth (60% to 70%) or up to two years of age (90%) and rare in adults. These malformations can occur in any region of the body, Lymphangiomas have marked predilection for the head and neck region (50% - 70%). The most common location in the mouth is the dorsum of tongue. If the positive diagnosis is generally easy, the therapeutic management remains controversial. We report the clinical case of a 23-year-old adult patient with cystic lymphangioma on the floor of the oral cavity extending gradually to the right submandibular region. The clinically suspected tumor was thoroughly explored using tomodensitometry. The treatment consisted of complete resection by a cervicotomy with histological examination confirming the macroscopic diagnosis of cystic lymphangioma. Follow-up at 3 years showed no recurrence.
文摘Lady Regio牌厕用卫生纸在投放市场不到一年的时间里，就被公认为墨西哥质量最好的卫生纸品牌。Copamex公司个人消费用卫生纸部门经理Juan Manuel Rojas先生对此解释道，“我们花大力气对市场和产品适用群体进行了研究，这一努力帮我们开发出了新的卫生纸产品，使墨西哥的消费者有了更多的选择范围。”据Rojas说，公司主要的策略是满足重要市场的特殊需求。
文摘A β-（1→）6）-branched β-（1→）3）-linked glucohexaose （1） and its lauryl glycoside （2）, present in many biologically active polysaccharides from traditional herbal medicines such as Ganoderma lucidum, Schizophyllum commune and Lentinus edodes, were highly efficiently synthesized. Coupling of 2,3,4,6-tetra-O-benzoyl-β-D-glucopyranosyl- （1--）3）-2-O-benzoyl-4,6-O-benzylidene-a-D-glucopyranosyl trichloroacetimidate （7） with 3,6-branched acceptors 8 and 12 gave β-（1→）3）-linked pentasaccharides （9） and （13）, then via simple chemical transformation 4＇,6＇-OH pentasaccharide acceptors 10 and 14 were obtained. Regio- and stereoselective coupling of 3 with 10 and 14 gave β-（1→）3）-linked hexasaccharides （11） and （15） as the major products. Deprotection of 11 and 15 provided the target sugar 1 and 2. Thus, a new method for the preparation of this kind of compounds was developed.
文摘A regio- and stereo-selective reduction of diketo-n-butylphosphonates by baker's yeast was reported. The chemical yield and ee value of these reactions are highly dependent on the structure of substrates. The resulting optical active hydroxy^alkanephosphonates can be used as chirons for the synthesis of polyfunctional organophosphorus compounds. As useful building block, a series of α,β-unsaturated ketones bearing chiral hydroxy group in addition to trifluoromethyl moiety was prepared via the Horner-Wadsworth-Emmons (HWE) reaction of the biotransformation products.
