B Amines

Scheme 4. Use of diversification linkers for the synthesis of (a) amides, (b) amines, (c) aromatic, and (d) heteroaromatic compounds.

MD simuations on low-energy [9-H-A] (A = alanine) docking geometries point to EXT as the thermodynamically most favored structures at room temperature. The relevant diastereomeric structures are almost equally stable. Therefore, the observed enantioselectivity has to be attributed to specific stabilization of the exhange transition structures. In this view, the small effects of the configuration of B Sb = (kfi/ks in Table 17) indicates that the B amine displaces alanine from the relevant EXT structure without getting completely into the chiral cavity of the host. 

The CSAs that have been used most widely are 2,2,2-trifluoro-l-phenylethanol (TFPE, la), 2,2,2-trifluoro-l-(l-naphthyl)ethanol (TFNE, lb), 2,2,2-trifluoro-l-(9-anthryl)ethanol (TFAE, Ic), 1-phenylethylamine (PEA, 2a), and l-(l-naphthyl)ethylamine (NEA, 2b). Both enantiomers of TFPE, TFAE (9), PEA, and NEA are commercially available. The fluoroalcohols are relatively acidic and interact strongly with solutes having one or more basic sites (Sect. IV-B). Amines 2 have been used most often as CSAs for organic acids or other acidic solutes (Sect. IV-C). A number of analogs of TFAE have been studied (Sect. III-C). 

Figure 2. Scheme illustrating (A) amine-silanol and (B) amine-amine interactions and (C) single site or site-isolated 3-aminopropyl groups grafted onto mesoporous silica [20]. 

Scheme 22 (a, b) Amination of the enantiopure alcohols 26a and 24a yields racemic cinnamyl and propargyl amides 27a and 25g. (c) Bismuth-catalyzed C-N bond cleavage makes this process reversible... 

Scheme 2 Allylic (a) and propargylic (b) aminations using optically active alcohols 6a and 6p...

Which of the molecules has four sp hybrid bonds B. amine... 

Nitril Reaktionsbedingungen b Amin Aus- beuted [%] Lite- ratur... 

Chemicals like HPic, HC104, R4NPK and BH+C104 (B=amine) must be handled with care because they are explosive. 

Fig. 13. Acylation via activation of a resin-bound carboxylic acid, (a) Pentafluorophenyl trifluoroacetate (6 equiv.) in Py/DMF (1 10), 1 h (b) amine (6 equiv.) CH2C12/DMF (c) TFA/ DCM (1 1) 1 h.

Ans. (a) alcohol (hydroxyl) (b) amine (tertiary amine) (c) ester (d) chloride (e) ketone (f) carboxylic acid (g) ester (triglyceride) (h) amide (i) ether (/ ) aldehyde (k) bromide (dibromide) (Z) alkyne (triple bond)... 

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