Showing papers by "B. Mark Heron published in 2005"
TL;DR: In this article, the synthesis and spectroscopic properties of 3H-naphtho[2,1-b]pyrans are described and a subtle variation of the color of the photo-generated merocyanine dyes derived from these naphthopyrans can be accomplished by controlling the steric interactions between a terminal pyrrolidine donor group and a proximal substituent.
40 citations
TL;DR: In this article, the crystal structure determined for one of the free ligands viz. 4-Pyrrolidine-1-yl-[1, 2] naphthaquinone thiosemicarbazone (5) indicates it to crystallize in the E' conformation which is supported by the NMR data.
36 citations
TL;DR: In this article, a range of new bi-photochromic molecules containing two identical (3a, d ) or two distinct naphthopyran units (6a − d ), linked through the phenyl substituents located on the sp 3 hybridised pyran ring carbon atom, using conjugated and non-conjugated spacers, have been synthesised from bis-propynols and (substituted)naphthols.
28 citations
TL;DR: 3-Acylchromones and 3-acylflavones undergo efficient conjugate reduction with NaBH 4 in pyridine to give the corresponding chroman-4-ones/flavanones in high yields in both regio- and chemoselective mode.
24 citations
21 citations
TL;DR: Developments in marine ladder polyethers that include synthetic studies on brevetoxin, ciguatoxinm, gambierol, gymnocin-A, and yessotoxin are discussed and their transformation into a range of useful products are discussed.
Abstract: Publisher Summary This chapter provides information on six-membered ring systems with O and/or S atoms. The chapter discusses heterocycles containing one oxygen atom, including pyrans, benzopyrans (chromenes), dihydrobenzopyrans (chromans), pyranones, coumarins, chromones, flavonoids, xanthones, and pyrylium salts. The chapter discusses heterocycles containing one sulfur atom, including thiopyrans and analogues. The chapter also discusses heterocycles containing two or more oxygen atoms, including dioxins, and trioxins. The chapter also discusses heterocycles containing two or more sulfur atoms, including dithianes, and trithianes. Oxathiines are discussed under heterocycles containing both oxygen and sulfur in the same ring. The hetero-Diels-Alder (HDA) reaction involving aldehydes is catalyzed by Pd(II) complexes, such that even non-activated dienes give satisfactory yields of 5,6-dihydro-2Hpyrans. Chiral aluminium complexes are effective in controlling both the chemo- and enantio- selectivity of the reaction of alkyl glyoxylates with dienes containing an allylic C-H bond; high yields of the dihydropyran result with enantiomeric excesses of up to 97%. Stannyl derivatives of 2H-pyran-2-one, accessible from bromopyranones by cross coupling with organotin reagents, themselves take part in Pd(0)-catalyzed cross coupling with enol triflates. This methodology offers a new approach to steroidal pyran-2-ones.
12 citations
TL;DR: In this article, the Suzuki-Miyaura couplings were used to synthesize 3-hydroxy and 6-hydroxyl derivatives of 11H-benzo[a]fluoren-11-one.
Abstract: Expedient syntheses of the 3-hydroxy- and 6-hydroxy- derivatives of 11H-benzo[a]fluoren-11-one, obtained via Suzuki-Miyaura couplings are described. Reactions of these phenols with 1,1-diarylprop-2-yn-1-ols give indeno[2,1-i]- and indeno[1,2-f]- naphtho[2,1-b]pyranones respectively. The photochromic properties of these and the reduced derivatives are reported. A rationale for the pronounced hypsochromic shift in λmax of the photomerocyanine from a 2H,9H-indeno[1,2-f]naphtho[2,1-b]pyran is presented.
2 citations
TL;DR: In this article, the 3-(Hydroxyalkyl)-1-naphthols 12 have been accessed in two steps from an isoquinolinium salt and were readily diazoacylated with ethyl diazomalonyl chloride.
Abstract: 3-(Hydroxyalkyl)-1-naphthols 12 have been accessed in two steps from an isoquinolinium salt. The naphthopyrans 15, derived from 12, were readily diazoacylated with ethyl diazomalonyl chloride. The carbenoid generated from 16 failed to undergo any cycloaddition and was instead intercepted by water to afford 18.
1 citations
TL;DR: In this article, the synthesis and spectroscopic properties of 3H-naphtho[2,1-b]pyrans are described and a subtle variation of the color of the photo-generated merocyanine dyes derived from these naphthopyrans can be accomplished by controlling the steric interactions between a terminal pyrrolidine donor group and a proximal substituent.
Abstract: The synthesis and spectroscopic properties of novel 3H-naphtho[2,1-b]pyrans are described. Subtle variation of the colour of the photo-generated merocyanine dyes derived from these naphthopyrans can be accomplished by controlling the steric interactions between a terminal pyrrolidine donor group and a proximal substituent.