Benzopyran

About: Benzopyran is a research topic. Over the lifetime, 1889 publications have been published within this topic receiving 15235 citations.

Direct α-Fluorination of Ketones Using N—-F Reagents.

Abstract: The use of 1-fluoro-4-hydroxy-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Accufluor NFTh) as a fluorine atom transfer reagent and methanol as solvent enabled direct regiospecific fluorofunctionalization of the u-carbonyl position in ketones without prior activation of the target molecules. Methoxy or hydroxy substituted derivatives of 1-indanone, 1-tetralone and oxo derivatives of thiophene, benzo[b]thiophene, benzofuran and benzopyran were regiospecifically transformed to the corresponding α-fluoro derivatives in high yield, while 2α-fluoro-5α-cholestan-3-one (28) and 16α-fluoro-3β-hydroxy-5α-androstan-17-one (30) were regio- and stereospecifically obtained starting directly from the corresponding keto steroids.

A Mild Synthesis of α,α′‐[Iminobismethylene]bis [6‐fluoro‐3,4‐dihydro‐2H‐1‐benzopyran‐2‐methanol].

Abstract: A new synthesis of α,α′-[iminobismethylene]bis[6-fluoro-3,4-dihydro-2H-1-benzopyran-2-methanol (1) is described, with most reactions being carried out at room temperature and normal pressure, that ...

Optimization and synthesis of (E)-4-[2-(3,4-dihydro-4,4-dimethyl-2H-1-benzopyran-6-y1)-1-propenyl]benzoic acid-11-[14C]

Abstract: Heteroarotinoids may be useful in the treatment of skin disorders and a wide variety of cancers. A synthesis of the C-14 labelled heteroarotinoid, (E)-4-[2-(3,4-dihydro-4,4-dimethyl-2H-1-benzopyran-6-yl)-1-propenyl]benzoic acid-11-[ 14 C] ( * 1) is described via a multistep procedure similar to that used to obtain the unlabelled compound 2. The latter has shown good activity in several assays compared to the standard trans-retinoic acid (3). Reduction of the carbonyl group in 4,4-dimethylchroman-6-yl methyl ketone-(carbonyl- 14 C) ( * 5) with LiAlH 4 gave alcohol * 6. Phosphorylation with triphenylphospine hydrobromide in methanol led to the corresponding phosphonium salt * 7. Addition of n-butyllithium to * 7 in ether at -78 °C generated the Wittig reagent in situ and to this was added ethyl 4-formylbenzoate. Workup and chromatography afforded E-ester * 8 and Z-ester * 9 which were both hydrolyzed to labelled * 1. Labelled * 1 was identical to unlabelled 2 in terms of spectral data and melting point. The specific activity of * 1 was determined to be 57.2 μCi/mg.