Chemistry of the Podocarpaceae. XLVIII. Photo-sensitized oxidations of unsaturated ring-c aromatic diterpenoids

1974 ◽  
Vol 27 (9) ◽  
pp. 2001 ◽  
Author(s):  
RC Cambie ◽  
RC Hayward
Keyword(s):  
Sodium Borohydride ◽  
Convenient Method ◽  
Lithium Aluminium ◽  
Enol Acetates ◽  
High Yields ◽  
General Method

Photo-sensitized oxidation of the 6,7-dehydro ring-c aromatic diterpenoids (5), (8) and (38) affords high yields of the corresponding 5-ene-7-ones (62), (63) and (69). Similar oxygenation of 13-methoxy- totara-6,8,11,13-triene (21) gives a hydroperoxide (74) which undergoes a facile rearrangement to a naphthyl derivative (80) in the presence of acid. Photo-sensitized oxidation of the enol acetates derived from the 7-oxo diterpenoids, however, provides a general method for preparation of the corresponding 5-ene-7-one. Reduction of the enone (62) with lithium aluminium hydridealuminium chloride gives a mixture of the 5,8,11,13-tetraene (66) and the 6,8,11,13-tetraene (9) while reduction with sodium borohydride and treatment of the resulting alcohols (61) and (67) with acid gives a mixture of the tetraenes (5) and (68). Photo-oxygenation of the latter mixture provides a convenient method for isolating the tetraene (68). Similar reductions of 13-methoxytotara-5,8,11,13-tetraen-7-one (76) have been examined and products from the action of m-chloroperbenzoic acid on the enol acetates (19), (20) and (7) are reported.

A CONVENIENT METHOD OF OBTAINING ASCOSPORES FROM BAKERS' YEAST

1949 ◽  
Vol 27c (4) ◽  
pp. 179-189 ◽  
Author(s):  
A. M. Adams
Keyword(s):  
Convenient Method ◽  
Sodium Acetate ◽  
Solid Medium ◽  
Genetic Research ◽  
Yeast Cells ◽  
Sporulation Medium ◽  
Direct Transfer ◽  
Yeast Cultures ◽  
High Yields ◽  
Solid Nutrient Medium

The superiority of methods involving the use of sporulation media containing acetate, first introduced by Stantial and Elder, over several commonly employed methods is established. A new method for obtaining ascospores from bakers' yeast cultures is recommended involving the direct transfer of vegetative cells from a solid nutrient medium to a solid medium containing acetate. High yields of ascospores are consistently produced after seven days' incubation. This method should lend itself particularly to use in the preparation of ascospores for instructional work, and for genetic research in yeast, and may also find application in yeast taxonomy. The technique recommended is as follows: vegetative yeast cells are multiplied on tomato juice agar or on dextrose nutrient agar, and are then transferred to a solid sporulation medium containing 0.04% dextrose, 0.14% anhydrous sodium acetate, and 2% agar.

AN IMPROVED PREPARATION OF ω-HYDROXY ALIPHATIC ACIDS AND THEIR ESTERS

1960 ◽  
Vol 38 (10) ◽  
pp. 1976-1982 ◽  
Author(s):  
D. G. M. Diaper ◽  
D. L. Mitchell
Keyword(s):  
Sodium Borohydride ◽  
Reductive Cleavage ◽  
Aliphatic Acids ◽  
Aliphatic Esters ◽  
High Yields

Reductive cleavage of the ozonides of aliphatic acids and their esters by sodium borohydride or by hydrogenation produces ω-hydroxy aliphatic acids and ω-hydroxy aliphatic esters, respectively, in high yields.

Flavan derivatives. XXIII. Preparation and synthetic applications of Flav-3-enes

1968 ◽  
Vol 21 (9) ◽  
pp. 2247 ◽  
Author(s):  
JW Clark-Lewis ◽  
RW Jemison
Keyword(s):  
Sodium Borohydride ◽  
Acidic Medium ◽  
Catalytic Reduction ◽  
Heterocyclic Ring ◽  
High Yield ◽  
Lithium Aluminium Hydride ◽  
Lower Field ◽  
Field Characteristic ◽  
Lithium Aluminium ◽  
New Synthesis

2'-Hydroxychalcones and α-alkoxy-2'-hydroxychalcones are converted by sodium borohydride in isopropanol into flav-3-enes and 3-alkoxyflav-3-enes in the convenient new synthesis which makes these flavenes readily available. Catalytic reduction of the flavenes gives the corresponding flavans or 3-alkoxyflavans in high yield, and the latter are obtained mainly in the 2,s-cis-form. The flavenes immediately give flavs lium cations in the cold when treated with acids in air, and oxidation of 5,7,3',4'-tetramethoxyflav-3-ene with benzoquinone in an acidic medium gave the flavylium salt, isolated as the ferrichloride. Reduction of 5,7,3',4'-tetramethoxy-flavylium chloride with lithium aluminium hydride gave 5,7,3',4'-tetramethoxy-flav-2-ene identical with the flavene obtained from (-)-epicatechin tetramethyl ether, and confirms an earlier investigation by Gramshaw, Johnson, and King. In its N.M.R. spectrum the heterocyclic-ring protons of this flav-2-ene give an ABX multiplet which is easily distinguished from the ABX multiplet at much lower field characteristic of flav-3-enes.

Reductions with sulfurated borohydrides. V. Reductions of ketones

1970 ◽  
Vol 48 (15) ◽  
pp. 2366-2371 ◽  
Author(s):  
J. M. Lalancette ◽  
A. Freche
Keyword(s):  
High Temperature ◽  
Carbonyl Group ◽  
Sodium Borohydride ◽  
Room Temperature ◽  
High Yield ◽  
High Yields ◽  
Very High

Ketones can be reduced with sulfurated sodium borohydride. Very high yield (≈90%) of the corresponding alcohol is obtained with the appropriate ratio of ketone and hydride at room temperature. The reaction is much influenced by the steric environment around the carbonyl group. At high temperature (65°) disulfides and tetrasulfides are produced. In some cases the structure of those sulfides have been established. Conjugated ketones can be reduced to the corresponding alcohols with very high yields.

ChemInform Abstract: Convenient Method for Reduction of C-N Double Bonds in Oximes, Imines, and Hydrazones Using Sodium Borohydride-Raney Ni System.

ChemInform ◽  
2012 ◽  
Vol 43 (46) ◽  
pp. no-no
Author(s):  
Yihua Yang ◽  
Shouxin Liu ◽  
Junzhang Li ◽  
Xia Tian ◽  
Xiaoli Zhen ◽  
...  
Keyword(s):  
Sodium Borohydride ◽  
Convenient Method ◽  
Double Bonds ◽  
Raney Ni

Reaction of 3,4a-disubstituted 4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestane derivatives with reducing agents

1985 ◽  
Vol 50 (11) ◽  
pp. 2457-2470 ◽  
Author(s):  
Helena Velgová ◽  
Jaroslav Zajíček
Keyword(s):  
Sodium Borohydride ◽  
Reducing Agents ◽  
Epoxide Ring ◽  
Lithium Aluminium Hydride ◽  
H Nmr ◽  
Lithium Aluminium ◽  
Nmr Data ◽  
Epoxy Alcohols

Reaction of all stereoisomeric 3-acetoxy-4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestan-4a-ols I-IV with lithium aluminium hydride and reduction of 3-acetoxy-4,4-dimethyl-5,6β-epoxy-A-homo-5β-cholestan-4a-ones XXII and XXIII with sodium borohydride were studied. It was found that reductive opening of the 5β,6β-epoxide ring occured only in the case of the derivatives III and IV due to 5(O)n participation of the 3α-oxygen-containing substituent under formation of the transannular 3α,5α-epoxides VIII and IX, resp. On reduction of the 4a-keto epoxides XXII and XXIII with sodium borohydride the trans-epoxy alcohols III and I were formed. On the basis of 1H NMR data the conformation of the A-ring in the epoxides I-IV, XXII, and XXIII is also discussed.

The synthesis of meso-Hexoestrol[3,4-D2] and some related specifically deuterated compounds

1974 ◽  
Vol 27 (8) ◽  
pp. 1743 ◽  
Author(s):  
DJ Collins ◽  
JJ Hobbs
Keyword(s):  
Methyl Ketone ◽  
Sodium Hydride ◽  
Dimethyl Sulphoxide ◽  
Reduction Sequence ◽  
Hydride Reduction ◽  
Lithium Aluminium ◽  
Methylmagnesium Iodide ◽  
High Yields ◽  
Unsaturated Nitrile ◽  
Hofmann Elimination

Condensation of p-methoxyphenylacetonitrile with p-methoxypropiophenone in the presence of sodium hydride in dimethyl sulphoxide at 65� gave (Z)-(23%) and (E)-2,3-bis(p-methoxyphenyl)pent-2-enenitrile(16%). The reduction of this α,β-unsaturated nitrile with lithium aluminium deuteride in tetrahydrofuran, and workup with D2O or with H2O, gave high yields of erythro-2,3-bis(p-methoxy-phenyl)valeronitrile[2,3-D2], or -[3-D], respectively. Conversion of the dideuteronitrile into the corresponding methyl ketone with methylmagnesium iodide, followed by a hydride reduction-tosylation-hydride reduction sequence, then demethylation, afforded meso-hexoestrol[3,4-D2]. Dehydration of (3RS,4SR)-3,4-bis(p-methoxyphenyl)hexan-2ξ-ol[3,4-D2] with phosphoryl trichloride in pyridine gave 3,4-bis(p-methoxyphenyl)hex-2-ene[4-D]. Reduction of erythro-2,3-bis(p-methoxy- phenyl)valeronitrile[3-D] to the corresponding amine followed by quaternization and Hofmann elimination afforded 2,3-bis(p-methoxypheny1)pent-1-ene[3-D].

Facile Synthesis of Thiols and Sulfides

1975 ◽  
Vol 53 (10) ◽  
pp. 1480-1483 ◽  
Author(s):  
Jean-Rock Brindle ◽  
Jean-Louis Liard
Keyword(s):  
Aromatic Ring ◽  
Sodium Borohydride ◽  
Facile Synthesis ◽  
Experimental Conditions ◽  
The Stability ◽  
High Yields

Sulfurated sodium borohydride reacts with benzylic halides to give high yields of α-toluenethiol or benzylic polysulfldes depending upon the experimental conditions and the mode of hydrolysis.Aliphatic halides and dibenzylic halides react in the same manner as benzylic halides for a given experimental condition whereas benzylic halides substituted with other groups can be totally or partially reduced depending on the stability of the substituent towards NaBH2S3.Halogens directly attached on the aromatic ring do not react with NaBH2S3.

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