Highly efficient synthesis of alka-1,3-dien-2-yltitanium compounds from alka-2,3-dienyl carbonates. A new, practical synthesis of 1,3-dienes and 2-iodo-1,3-dienes
摘要:
Treatment of carbonates of alka-2,3-dien-1-ols 2 with (eta(2)-propene)Ti(O-i-Pr)(2) (I) resulted in oxidative addition to afford 1,3-dien-2-yltitanium compounds 3, which react readily with electrophiles such as H+, I-2 and aldehydes. The reaction with H+ and I-2 proceeds highly regioselectively, thus providing an efficient and practical method for synthesis of 1,3-dienes and 2-iodo-1,3-dienes. Copyright (C) 1996 Elsevier Science Ltd.
Regiospecific allylation of acetals with allylsilanes catalyzed by iodotrimethylsilane. Synthesis of homoallylethers
作者:Hideki Sakurai、Koshi Sasaki、Akira Hosomi
DOI:10.1016/0040-4039(81)80140-2
日期:1981.1
Allylation of acetals with allylsilanes is catalyzed by iodotrimethylsilane to give the corresponding homoallyl ethers, with regiospecific transposition of the allyl group.
1-Alkenyl cyclopropylketones, when activated by cation-stabilizing substituents at the ring carbon or at the terminal carbon of the enone moiety, undergo polyphosphoric acid-catalyzed ring enlargement producing cyclopentanone or cyclohexenone derivatives. Similar acid-catalyzed ring opening of 1-alkenyl 2-phenoxycyclopropyl ketones offers a convenient and effective synthesis of 4-oxo-5-alkenals and
SYNTHESIS OF 2-(TRIMETHYLSILYL)- AND 2-(DIETHOXYPHOSPHONYL)-1,3-BUTADIENES
作者:Valerij Ch. Christov
DOI:10.1080/10426509808036976
日期:1998.1.1
Abstract Synthesis of the 2-(trimethylsilyl)- (3) and the 2-(diethoxyphosphonyl)-1,3-butadienes (4) by Homer-Emmons and Peterson reactions respectively, of the 1-(trimethylsilyl)-2-propenylphosphonic diethyl ester (1) is described.
The invention provides N-cyclic sulfonamido compounds of Formula I
wherein A, B, R
1,
R
1a,
R
2
, R
2a,
R
3
and R
3a
are as described in the specification. Compounds of Formula I are useful in treating or preventing cognitive disorders, such as Alzheimer's disease. The invention also encompasses pharmaceutical compositions comprising compounds of Formula I, methods of preparing compounds of formula I, and methods of treating cognitive disorders, such as Alzheimer's disease.
The invention provides N-cyclic sulfonamido compounds of Formula I
wherein A, B, R1, R1a, R2, R2a, R3 and R3a are as described in the specification. Compounds of Formula I are useful in treating or preventing cognitive disorders, such as Alzheimer's disease. The invention also encompasses pharmaceutical compositions comprising compounds of Formula I, methods of preparing compounds of formula I, and methods of treating cognitive disorders, such as Alzheimer's disease.