Enolic Ortho Esters. III. Preparation of a Keto Acetal by Hydride Reduction of an Enolic Ortho Ester

1989 ◽  
Vol 42 (9) ◽  
pp. 1617 ◽  
Author(s):  
DJ Collins ◽  
LM Downes ◽  
M Kyriakou
Keyword(s):  
Lithium Aluminium Hydride ◽  
Ortho Ester ◽  
Hydride Reduction ◽  
Lithium Aluminium ◽  
High Yields ◽  
Ortho Esters

Lithium aluminium hydride reduction of the enolic ortho ester 4′,4′-dimethyl-3,4,5,8-tetra-hydrospiro [2H-l-benzopyran-2,21-[1,3]dioxolan] (8) in the absence of solvent gave 6-[21-(4″,4″- dimethyl-1″,3″-dioxolan-2″-yl)ethyl]cyclohex-3-en-1-one (11) which was isomerized to the α'β-unsaturated keto acetal (10). Similarly, hydride reduction of the phenolic ortho ester 4′-methyl-3,4-dihydrospiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (12a) and the 4′,4′-dimethyl analogue (12b), afforded the corresponding phenolic acetals (14a) and (14b) respectively, in high yields.′

Lithium aluminium hydride reduction of some organo-sulphur compounds.

1967 ◽  
Vol 8 (11) ◽  
pp. 971-974 ◽  
Author(s):  
Kazi Abdul Latif ◽  
Paritosh Kumar Chakraborty
Keyword(s):  
Lithium Aluminium Hydride ◽  
Sulphur Compounds ◽  
Hydride Reduction ◽  
Lithium Aluminium

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].

Enolic Ortho Esters. I. Preparation and Birch Reduction of Some Coumarinoid Ortho Esters

1989 ◽  
Vol 42 (8) ◽  
pp. 1235 ◽  
Author(s):  
DJ Collins ◽  
LM Downes ◽  
AG Jhingran ◽  
SB Rutschmann ◽  
GJ Sharp
Keyword(s):  
Carbon Tetrachloride ◽  
Acid Hydrolysis ◽  
Boron Trifluoride ◽  
Boron Trifluoride Etherate ◽  
High Yield ◽  
Ortho Ester ◽  
Birch Reduction ◽  
High Yields ◽  
Ortho Esters ◽  
Hydrolysis Of

Phenolic ortho esters such as 4′,4′-dimethylspiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (7b) and 4′,4′-dimethyl-3,4-dihydrospiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (9c) were prepared in low yields by reaction of 2H-1-benzopyran-2-one (5) or 3,4-dihydro-2H-1-benzopyran-2-one (8a) with 2,2-dimethyloxiran in carbon tetrachloride in the presence of boron trifluoride etherate. 3,4-Dihydrospiro[2H-1-benzopyran-2,2′-[1,3] dioxoan ] (9a) and the corresponding 7-methoxy compound (9e) were obtained in high yield by reaction of (8a) or its 7-methoxy analogue (8b) with 1,2-bis(trimethylsily1oxy)ethane (10) in the presence of trimethylsilyl trifluoromethane-sulfonate . Birch reduction of phenolic ortho esters such as (9c) and (9e) afforded the enolic ortho esters 4′,4′-dimethyl-3,4,5,8-tetrahydrospiro[2H-1-benzopyran-2,2′-[1,3] dioxola n] (11a) and 7-methoxy-3,4,5,8-tetrahydrospiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (llc) in high yields. Birch reduction of 4′,4′,5′,5′-tetramethylspiro[2H-1-benzopyran-2,2′-[1,3]dioxolan] (7c) gave a 1 : 3 mixture of 4′,4′,5′,5′-tetramethyl-3,4-dihydrospiro[2H-1-benzopyran-2,2′-[l,3] dioxolan ] (9d) and the corresponding 3,4,5,8-tetrahydro compound (11b). Acid hydrolysis of the enolic ortho ester (11a) gave 67% of 2-hydroxy-2-methylpropyl 3-(2-oxocyclohex-3-enyl) propanoate (20).

scholarly journals Lithium Aluminium Hydride Reduction of Pregnenolone under Conditions of Assumed Kinetic and Equilibrium Control.

1981 ◽  
Vol 35b ◽  
pp. 407-410 ◽  
Author(s):  
Stig Allenmark ◽  
Hans Borén ◽  
Bertil Samuelsson ◽  
Bertil Samuelsson ◽  
Ulrika Örn
Keyword(s):  
Lithium Aluminium Hydride ◽  
Hydride Reduction ◽  
Lithium Aluminium ◽  
Equilibrium Control
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