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PubMed1996

Synthesis of Enantiopure Primary Amines by Stereoselective Ring Opening of Chiral Octahydro-1,3-benzoxazines by Grignard and Organoaluminum Reagents.

Chiral 1,3-perhydrobenzoxazines 1, 2, and 9-14, prepared by condensation of 8-(benzylamino)menthol with different aldehydes, react with alkylmagnesium bromides and trimethylaluminum leading to the open amino alcohols 3a-d, 4a-d, and 15-20 in excellent chemical yields and good to excellent diastereomeric excess. The sequential elimination of the menthol appendage by heating with P(2)O(5) and the benzyl group by hydrogenolysis lead to primary amines 7a-d, 8a-d, and 27-30 in excellent chemical yields and ee. The addition of the alkyl group from the Grignard derivatives and the methyl group from the trimethylaluminum occurs from opposite sides of the heterocycle, yielding the final primary amines with the same stereochemistry.

Journal Article↗
PubMed1997

2-Substituted 2,3-Dihydro-4H-1,3-benzoxazin-4-ones: Novel Auxiliaries for Stereoselective Synthesis of 1-beta-Methylcarbapenems(1).

The dihydrobenzoxazone 9e, which is easily prepared from salicylamide 11 and cyclohexanone, serves as an efficient auxiliary in the synthesis of the 1-beta-methylcarbapenem key intermediate 10. The stereocontrolled Reformatsky-type reactions of the acetoxyazetidinone 2 with the carboximides 6 gave the intermediates 7 with high diastereoselectivities in high chemical yields. The auxiliary 9e also acts as a good leaving group in the TMSCl-promoted Dieckmann-type cyclization leading to a 1-beta-methylcarbapenem skeleton. By using this auxiliary, 10 was synthesized in 58% overall yield and four steps from 2.

Journal Article↗
PubMedDate not supplied

Contents of 1,4-benzoxazin-3-ones and 2-benzoxazolinone from Stenandrium dulce (Nees).

Secondary metabolites, DIBOA, HBOA, 7-OH-HBOA and BOA, were isolated and quantified from S. dulce (Nees), a native species in Chile belonging to the Acanthaceae family. The highest DIBOA and HBOA contents were determined in leaves (9.25 mmol kg(-1) fr. wt) and root (6.81 mmol kg(-1) fr. wt), respectively. Aglycones, 7-OH-HBOA and HBOA, were isolated together from root extracts of Acanthaceae species. Both, HBOA and 7-OH-HBOA should be direct precursors in the biosynthesis of DIBOA and DIMBOA, respectively.

Acanthaceae↗
PubMed2000

Synthesis and binding studies on a new series of arylpiperazino benzazol-2-one and benzoxazin-3-one derivatives as selective D4 ligands.

A series of new arylpiperazinomethyl derivatives was designed and studied as potential D4 ligands. The synthesis of these compounds required an original synthetic route. Some of the tested compounds were found to be as potent as clozapine at D4 receptors. Moreover, compounds which displayed a high D2/D4 selectivity ratio (>122) were selected for further pharmacological evaluation.

Azoles↗