Boron Enolate
Mostrando 1-6 de 6 artigos, teses e dissertações.
-
1. Estudo do efeito do substituinte em ß nas reações aldólicas envolvendo enolatos de boro de metilcetonas / Investigation of the influence of ß substituent in aldol reactions involving boron enolates of methylketones
As reações aldólicas envolvendo os enolatos de boro 71 (P = TBS, R = t-Bu), 72 (P = PMB, R = t-Bu) e 96 (P = TPS, R = t-Bu) levaram à formação de adutos de aldol com seletividades de moderadas a boas em favor do isômero 1,5-syn. As reações aldólicas envolvendo os enolatos de boro 90 (P = Tr, R = t-Bu), 91 (P = Tr, R = Me) e 97 (P = TPS, R = Me) lev
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 21/02/2011
-
2. Controle da estereoquímica remota 1,5 em adições de enolatos de boro de metilcetonas a aldeídos / Control of 1,5 remote stereochemistry in additions of boron enolates of methylketones to aldehydes
The aldol reactions of the boron enolate generated from methylketone 44 (containing a trans-acetonide), led to aldol adducts with moderate to good levels of diastereoselectivity, favoring the 1,5-anti adduct. The aldol reactions involving the boron enolate of methylketone 45 (containing a cis-acetonide) gave the corresponding aldol adducts with excellent lev
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 18/02/2011
-
3. Indução assimétrica 1,5-Anti na adição de enolatos de boro de metilcetonas beta-oxigenadas a aldeídos
High levels of substrate-based 1,5-stereoinduction are obtained in the boron-mediated aldol reactions of beta-oxygenated methyl ketones with achiral and chiral aldehydes. Remote induction from the boron enolates gives the 1,5-anti adducts, with the enolate pi-facial selectivity critically dependent upon the nature of the beta-alkoxy protecting group. This 1,
Química Nova. Publicado em: 2007
-
4. Adição diastereosseletiva de nucleofilos de carbono a ions N-aciliminios ciclicos: Aplicação na síntese de sistemas pirrolizidínico e indolizidínico monosubstituidos
Good diastereoeselection was observed in the addition of the carbon nucleophiles derived from S-tert-butyl thiopropionate 84, S-phenyl thiopropionate 96 and tert-butyl propionate 95 to the 6-membered N-acyliminium ion derived from 2-ethoxy carbamate 80. The 2RS, 1 SR relative stereochemistry of the major isomer formed in the addition of O-silylketeneacetal d
Publicado em: 1998
-
5. Sintese total e enantiosseletiva da aglicona do antibiotico (+)-10-desoximetimicina
This work describes the enantioselective total synthesis of (+)-10-Deoxymethynolide (2c), the aglycon of the 12-membered macrolide antibiotic 10-Deoxymethymycin, through the esterification of the C1-C7 and C8-C13 fragments ((-)-339 and (+)-346, respectively) and macrocyclization of the corresponding vinylic iodide-aldehyde via an intramolecular Nozaki- Hiyam
Publicado em: 1998
-
6. Adição de nucleofilos de carbono a ions iminio e aciliminio : sintese de B-aminocetonas e enantiosseletiva da base necinica (+) - hastanecina
b-aminoketones 50-58 and 67-70 were prepared in 35-80% yield through the addition of sililenolethers to iminiun ions generated from the corresponding imines (Schiff bases) and 15% mol of TMSOTf or catalytic amount of Lewis acid (Cp2BOTf, BF3 OEt2, Me2AlCI ou TiC4). The diastereoisomeric ratio of the b-aminoketones proved to be dependent on the reaction condi
Publicado em: 1995