Beta substitutions

Casanola-Martin GM et al. (2006) New tyrosinase inhibitors selected by atomic linear indices-based classification models. Bioorg Med Chem Lett 16(2) 324-330 Tan CY, Wainman D, Weaver DF (2003) N-, alpha-, and beta-substituted 3-amino-propionic acids design, syntheses and antiseizure activities. Bioorg Med Chem 11(1) 113-121... 

In contrast to 1, the related pure host 7 may be obtained in crystalline form 68). The crystal structure of 7 is built via helical chains of alternating intra- and inter-molecular H-bonding through the carboxyl functions. This structure supplies the information that the carboxyl groups are therefore already positioned in an appropriate way to facilitate analogous H-bonding in the known inclusions of 7. As discussed later (Sect. 4.2.2), these are exclusively salt-type associates and as such, intimately interact with the carboxyl groups. Hence one may infer that displacement of the carboxyl functions from position 2 in 1 to position 8 in 7 reduces the ability of inclusion formation. Similar reasons such as the solid-solubility differences observed in the classical naphthalene/chloronaphthalene systems (alpha- vs. beta-substituted derivatives, cf. Ref. 28 may also be applied here. 

Tertiary amines of class (iii) were also studied by Lunazzi and coworkers75. A series of beta-substituted-alpha-amino naphthalenes 41a-d-44a-d were investigated using DNMR and NOE experiments and molecular mechanics. Such systems allow for separation between rotational processes, whose barriers around Ar—N bonds are quite high (15-23 kcal mol 1). and inversion, known to have particularly low barriers... 

Table 3.9. ANTAGONIST ACTIVITY OE C-I4 BETA-SUBSTITUTED MORPHINE...

Marnett LJ, Basu AK, O Hara SM. 1986. The role of cyclic nucleic acid adducts in the mutational specificity of malondialdehyde and beta-substituted acroleins in Salmonella. IARC Sci Publ... 

The heavy-atom effect of substituents introduced in a porphyrin will depend on the substitution pattern and may be different for Si Ti and Ti So transitions. Thus, it should be possible to control the electronic factor to increase the triplet quantum yield without compromising its lifetime. This hypothesis was investigated in detail using various meso- and beta-substituted free-base and Mg, Zn, or Cd metalloporphyrins (53). It was considered that the spin-orbit coupling of atoms in identical substitution patterns gives additive contributions to the nonadiabatic factor... 

JK Kim, MC Findlay WG Henderson, MC Caserio. Ion cyclotron resonance spectroscopy Neighbouring group effects in the gas-phase ionization of beta-substituted alcohols. J Am Chem Soc 95 2184—2193, 1973. 

The synthesis and agonist activity of some 14.beta.-substituted morphine and codeine derivatives... 

Synthesis and analgesic activity of somel4.beta.-substituted analogs of morphine Osei-Gyimah, Peter Archer, Sydney... 

Marcotte, P.A. and C.H. Robinson (1982). Synthesis and evaluation of 10-beta-substituted 4-estrene-3,17-diones as inhibitors of human placental microsomal aromatase. Steroids 39, 325-344. 

Naphthalene and Derivatives. The time-temperature relationship is especially important in this series from the standpdnt of isomer distribution. Low temperatures (SO C and below) and/or diort reaction periods favor alpha substitution, while higher tena(peratures (about 160 C) and/or a longer time favor beta substitution. Even when the more stable beta isomer is the final product, the less stable (but more easily formed) alpha isomer is produced first, but imdergoes desulfonation and resulfonatimi to the beta sulfonate. The data for naphth ene are shown in Table 7-11. The same considerations hold in the disulfonation of naphthalene and in the preparation of the naphthd- and naphthylaminesuHonic acids. 

Yu H, Prisinzano T, Dersch CM, Marcus J, Rothman RB, Jacobson AE, Rice KC (2002) Synthesis and biological activity of 8 beta-substituted hydrocodone indole and hydromorphone indole derivatives. Bioorg Med Chem Lett 12 165-168... 

From the data presented, it is clear that the tetrameric macrocycles bind alpha substituted naphthalene derivatives, simple aromatic compounds or 1-amino-adamantane very poorly, a beta substituted... 

Dabrowski JA, Gao F, Hoveyda AH (2011) Enantioselective synthesis of alkyne-substituted quaternary carbon stereogenic centers through NHC-Cu-catalyzed allylic substitution reactions with ( Bu)2(alkynyl)aIuminum reagoits. J Am Chem Soc 133 4778-4781 Fananas-Mastral M, Feringa BL (2010) Copper-catalyzed regio- and enantioselective synthesis of chiral enol acetates and beta-substituted aldehydes. J Am Chem Soc 132 13152-13153... 

Chen, l.-Hon, Yin, L., Itano, W., Kanai, M., Shibasaki, M. 2009. Catalytic asymmetric synthesis of chiral tertiary organoboronic esters through conjugate boration of beta-substituted cyclic enones. J. Am. Chem. Soc. 131 11664-11665. 

Enders D, Schubert H. Enantioselective synthesis of beta-substituted primary amines -alkylation reductive amination of aldehydes via samp-hydrazones. Angew. Chem. Int. Ed. Eng. 1984 23 365-366. 

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