Rhodium-Catalyzed Enantioselective 1,2-Addition of ArylboronicReagents to α-Ketoesters using Chiral Diene Ligands
本研究是以「tert-butyl 2-oxo-2-phenylacetate 進行 1,2-不對稱加成製備成 tert-butyl 2-hydroxy-2,2-diphenylacetate之最適化實驗」做為實驗目標,在起始物的苯環上添加不同的取代基進行反應,以探討不同的 tert-butyl 2-oxo-2-phenylacetate 衍生物產率及鏡像超越值的差異。研究結果顯示,在以取代基位置為操作變因的實驗中,間位、對位擁有 48% 及 43% 的產率,鄰位產率則僅有 12% ,但鏡像超越值皆能達 >90% ee。由此可推論鄰位因有較大的立體阻礙,使得反應不易發生;間位雖比對位有較高的立體阻礙,但因與反應處相距較遠,故影響較小;而鏡像選擇性不受立體阻礙影響。為了使間位和對位反應的差異更為明顯,故決定在間位及對位以不同電子效應的基團做為取代基進行反應。研究結果也顯示,當間位具有一個拉電子特性的 CF3取代基,能使 α–ketoester 之加成產物產率>99%。未來若能進一步以更多不同的推拉電子基做為取代基,則可望使立體阻礙大小與推拉電子效應被量化,進而預測產率,協助進行最適化製備的研究過程中,更有效率的找到最適化條件。
A STUDY ON TRADITIONAL ARCHITECTURE IN ITANAGAR CAPITAL COMPLEX AND TO IMPROVE A MODIFIED TYPOLOGY FOR A CLIMATE RESPONSIVE CONTEMPORY HOUSE
The lifestyle of the Arunachal Pradesh rural population demonstrates the example of sustainable living where bamboo plays a major role. Bamboo has its home in this tropical climate region of India. In order to understand various aspects of traditional bamboo constructions, a field visit was made to Rono, Emchi, Lekhi villages and Karsingsa, Pachin, NEEPCO areas. The paper studies the patterns affecting the housing styles of these regions, the traditional method of construction including bamboo treatments. Various parameters which are required to be considered for constructing a house are also studied. It has been found in the field survey that the utilization of bamboo is mostly in wall panels, columns, floor, door and windows. The question posed here is whether tradition houses perform better than a typical contemporary house in creating comfortable internal conditions. And if they do how it is possible for the contemporary house to benefit from the advantages presented in the design of the traditional house in terms of thermal performance. The results indicate that improved performance might be achieved by combining selected lessons from the traditional design e.g. improved shading, regional variations in window size related to orientation and adoption of adjustable ventilation and window openings.