نتایج جستجو برای: dental auxiliaries

تعداد نتایج: 162392  

Journal: :Organic letters 2013
Lin Hao Shaojin Chen Jianfeng Xu Bhoopendra Tiwari Zhenqian Fu Tong Li Jieyan Lim Yonggui Robin Chi

Asymmetric functionalization of alkylacetic esters and their derivatives is traditionally achieved via preformed enolates with chiral auxiliaries. Catalytic versions of such transformations are attractive but challenging. A direct catalytic activation of simple alkylacetic esters via N-heterocyclic carbene organocatalysts to generate chiral enolate intermediates for highly enantioselective reac...

Journal: :Chemical communications 2010
Iria Louzao José Manuel Seco Emilio Quiñoá Ricardo Riguera

(13)C NMR, alone or in combination with (1)H NMR, allows the assignment of the absolute configuration of chiral alcohols, amines, carboxylic acids, thiols, cyanohydrins, sec,sec-diols and sec,sec-aminoalcohols, derivatized with appropriate chiral auxiliaries. This extends the assignment possibilities of NMR to fully deuterated and to nonproton containing compounds.

2013
Quynh Pham Bao Nguyen Taek Hyeon Kim

Asymmetric alkylation reactions using non-cross-linked polystyrene (NCPS)-supported 2-imidazolidinone chiral auxiliaries were successfully investigated with excellent diastereocontrol (>99% de). The recovery and the recycling of this soluble polymer-supported chiral auxiliary were achieved in order to produce highly optical pure carboxylic acids.

Journal: :Journal of the American Chemical Society 2005
Michael T Crimmins Hamish S Christie Kleem Chaudhary Alan Long

An efficient, enantioselective synthesis of apoptolidinone has been completed, demonstrating the versatility of thiazolidinethione auxiliaries. Three propionate aldol additions and two asymmetric glycolate alkylations function to establish 8 of the 12 stereogenic carbon centers. A cross-metathesis reaction is utilized to assemble the C1-C10 trieneoate fragment and the C11-C28 polypropionate reg...

Journal: :Chemical communications 2014
Christina M McSweeney Vera M Foley Gerard P McGlacken

The asymmetric alkylation of ketones represents a fundamental transformation in organic chemistry. Chiral auxiliaries have been used almost exclusively for this transformation. Herein we describe a strategy for the generation of enantiomerically enriched α-alkylated ketones up to an er of 83 : 17, using a chiral ligand protocol.

Journal: :Vestnik Sankt-Peterburgskogo universiteta 2022

As benefactives in other languages of the world, Japanese benefactive constructions can be used various meanings apart from core meaning. In previous research their semantics is normally described separately for each auxiliary verbs, and itself based either on introspection or working with sporadic texts native-speakers. this article we present a qualitative quantitative analysis corpora datase...

Journal: :Organic letters 2007
Michael T Crimmins Mariam Shamszad

[reaction: see text] Highly diastereoselective acetate aldol additions using chlorotitanium enolates of mesityl-substituted N-acetyloxazolidinethione and N-acetylthiazolidinethione auxiliaries are reported. These additions proceed in high yields and diastereoselectivities (93:7 to 98:2) for aliphatic, aromatic, and ,-unsaturated aldehydes. Double diastereoselective acetate aldol additions are a...

Journal: :Evidence-based nursing 2002
Laurel E Radwin

Participants 19 English speaking carers who attended the ward and 25 healthcare workers. Informal carers were those who provided physical or social care or assistance for another person. Without this help, the recipient would need health, social, or voluntary sector service intervention. Healthcare workers were nurses, physiotherapists, occupational therapists, dieticians, ambulance personnel, ...

پایان نامه :وزارت بهداشت، درمان و آموزش پزشکی - دانشگاه علوم پزشکی و خدمات بهداشتی درمانی استان سیستان و بلوچستان 1379

با توجه به نقش مهم جرم دندانی ‏‎(dental calculus)‎‏و التهاب لثه ‏‎(gingival inflammation)‎‏ در ایجاد بیماریهای تخریب کننده پریودنتال و نیز با توجه به شیوع فراوان بیماریهای لثه و پریودنتال در میان جمعیت ها، اهمیت نیاز به اطلاعات آماری دقیقی که بتواند نمایانگر وضعیت بهداشتی جامعه باشد، روشن می گردد. این مطالعه به منظور بررسی شاخص های خونریزی لثه ‏‎(gingival bleeding)‎‏ تحلیل لثه ‏‎(gingival reces...

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