Conformational analysis. XX. Stereochemistry of reaction of Grignard reagents with ortho esters. Synthesis of 1,3-dioxanes with axial substituents at C-2

1970 ◽  
Vol 92 (3) ◽  
pp. 584-590 ◽  
Author(s):  
Ernest L. Eliel ◽  
Franz W. Nader
Keyword(s):  
Conformational Analysis ◽  
Grignard Reagents ◽  
Ortho Esters

Enolic Ortho Esters. VII Involvement of Magnesium Halides as Lewis Acids in the Reaction of Grignard Reagents with 1,6-Dideoxy- 1,1-ethylenedioxy-2,3,4-tri-O-methyl-D-xylo-hex-5- enopyranose and its 6-Phenyl Derivative: a Correction

1998 ◽  
Vol 51 (8) ◽  
pp. 681 ◽  
Author(s):  
David J. Collins ◽  
Angus I. Hibberd ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Single Crystal ◽  
Lewis Acids ◽  
Titanium Tetrachloride ◽  
Grignard Reagents ◽  
Ortho Ester ◽  
X Ray ◽  
Phenyl Derivative ◽  
Methylmagnesium Iodide ◽  
Ortho Esters ◽  
Phenylmagnesium Bromide

The known aldehyde methyl 2,3,4-tri-O-methyl-α-D-gluco-hexodialdo-1,5-pyranoside (9) was converted in eight steps into the 6-phenyl glucose-derived enolic ortho ester (Z)-1,6-dideoxy-1,1-ethylenedioxy- 2,3,4-tri-O-methyl-6-phenyl-D-xylo-hex-5-enopyranose (22), the geometry of which was established by a single-crystal X-ray study. Treatment of the 6-phenyl enolic ortho ester (22) with titanium tetrachloride at –78° effected clean rearrangement into (2R/S,4R,5R,6S)-3,3-ethylenedioxy-4,5,6-trimethoxy-2-phenylcyclohexanone (26). Reaction of (22) with methylmagnesium iodide gave (1R,2S,4R,5S,6S)-3,3-ethylenedioxy-4,5,6-trimethoxy-1-methyl-2-phenylcyclohexanol (24), the structure and stereochemistry of which were established by an X-ray study. Reaction of (22) with phenylmagnesium bromide gave (25), the 1-phenyl analogue of (24). The firmly established structure of (24) led to proof both chemically and by X-ray means that the product from reaction of 1,6-dideoxy-1,1-ethylenedioxy-2,3,4-tri-O-methyl-D-xylo-hex-5-enopyranose (5) with methylmagnesium iodide has the hydroxy acetal structure (7) rather than the originally assigned hemiacetal structure (3).

A facile synthesis of 3,4-dialkyl-3,4-dihydro-2H-1,3-benzoxazin-2-ones and naphthoxazin-2-ones and their reactions with organolithium and Grignard reagents – Preparation of N-[1-(2′-hydroxyphenyl)alkyl]amides

2004 ◽  
Vol 82 (8) ◽  
pp. 1314-1321 ◽  
Author(s):  
Cristina Cimarelli ◽  
Gianni Palmieri ◽  
Emanuela Volpini
Keyword(s):  
Reaction Mechanism ◽  
Conformational Analysis ◽  
Grignard Reagents ◽  
Facile Synthesis ◽  
Simple Method ◽  
Relative Configuration ◽  
Organometallic Reagents ◽  
H Nmr ◽  
High Yields

A facile and simple method for the preparation of 3,4-dialkyl-3,4-dihydro-2H-1,3-benzoxazin-2-ones or naphthoxazin-2-ones in high yields from aminoalkylphenols and aminoalkylnaphthols is described. The reactions of the products obtained with organolithium and Grignard reagents were studied, and a method for the preparation of N-[1-(2-hydroxyphenyl)alkyl]-N-alkylamides, which are of pharmaceutical interest, from benzoxazinones was developed. A possible reaction mechanism is also proposed. The relative configuration of chiral products was determined from conformational analysis of 1H NMR spectra.Key words: benzoxazinones, naphthoxazinones, organometallic reagents, amide preparation, aminoalkylphenols.

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