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트리아릴포스포늄 염과 카르보닐 화합물 사이의 위티그 반응의 입체선택성에 대한 고압 효과
김정성,최정훈,지진영,김창만,김용훈 대구대학교 기초과학연구소 1999 基礎科學硏究 Vol.15 No.3
The Wittig reactions of triarylphosphonium ylides with various carbonyl compounds under high pressure were carried out to investigate its effect on the cis-trans stereochemical outcome. Generally, the cis-stereoselectivities at atmospheric pressure are known to be resulted from smaller steric hindrance of α-carbon of carbonyl group with hydrogens of phenyl residue of triphenylphosphonium ylide and in oxaphosphetane intermediate stage. Thus, the steric interactions between triphenylphosphonium ylide and carbonyl compounds in the transition state can be maximized. And, the reactions of semistabilized ylide and stabilized ylide at atmospheric pressure generate mainly thermodynamically more stable trans-alkane after formation of betaine intermediate. The reactions at high pressure, however, can generate cis-alkene more exclusively through oxaphosphentane intermediate,directly without the formation of betaine intermediate by reducing distance between ylide and carbonyl compound. Reaction between benzyl triphenylphosphonium ylide, a semistabilized ylide, and butyraldehyde at atmospheric pressure gave cis-1-phenyl-1-pentene with 34/66 of Z/E stereoselectivity, but when pressurized at 10000 bar, cis-alkene with 69/31 the Z/E ratio was excellently yielded than trans-alkene. In the case of Wittig reaction of ethoxyacetyl triphenylphosphonium ylide, a stabilized ylide, with butyraldehyde, Z/E stereoselectivity at 10000 bar was inversed in contrast to atmospheric pressure.
김지연,배성만,박순주,권지수,임소윤,박지영,차혜희,서미현,이현정,이나경,허진영,Shum David,지영미,김성한 대한면역학회 2021 Immune Network Vol.21 No.4
There are limited data directly comparing humoral and T cell responses to the ChAdOx1 nCoV-19 and BNT162b2 vaccines. We compared Ab and T cell responses after first doses of ChAdOx1 nCoV-19 vs. BNT162b2 vaccines. We enrolled healthcare workers who received ChAdOx1 nCoV-19 or BNT162b2 vaccine in Seoul, Korea. Anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) S1 protein-specific IgG Abs (S1-IgG), neutralizing Abs (NT Abs), and SARS-CoV-2-specific T cell response were evaluated before vaccination and at 1-wk intervals for 3 wks after vaccination. A total of 76 persons, comprising 40 injected with the ChAdOx1 vaccine and 36 injected with the BNT162b2 vaccine, participated in this study. At 3 wks after vaccination, the mean levels (±SD) of S1-IgG and NT Abs in the BNT162b2 participants were significantly higher than in the ChAdOx1 participants (S1-IgG, 14.03±7.20 vs. 6.28±8.87, p<0.0001; NT Ab, 183.1±155.6 vs. 116.6±116.2, p=0.035), respectively. However, the mean values of the T cell responses in the 2 groups were comparable after 2 wks. The humoral immune response after the 1st dose of BNT162b2 developed faster and was stronger than after the 1st dose of ChAdOx1. However, the T cell responses to BNT162b2 and ChAdOx1 were similar.