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All total 11 Articles be found
All total 11 Articles be foundTriphenylphosphine Oxide-Catalyzed Selective α,β-Reduction of Conjugated Polyunsaturated Ketones
Xia, Xuanshu,Lao, Zhiqi,Toy, Patrick H.
supporting information, p. 1100 - 1104 (2019/05/24)
The scope of the triphenylphosphine oxide-catalyzed reduction of conjugated polyunsaturated ketones using trichlorosilane as the reducing reagent has been examined. In all cases studied, the α,β-C=C double bond was selectively reduced to a C-C single bond while all other reducible functional groups remained unchanged. This reaction was applied to a large variety of conjugated dienones, a trienone, and a tetraenone. Additionally, a tandem one-pot Wittig/conjugate-reduction reaction sequence was developed to produce γ,δ-unsaturated ketones directly from simple building blocks. In these reactions the byproduct of the Wittig reaction served as the catalyst for the reduction reaction. This strategy was then used in the synthesis of naturally occurring moth pheromones to demonstrate its utility in the context of natural-product synthesis.
The preparation and electrocyclic ring-opening of cyclobutenes: Stereocontrolled approaches to substituted conjugated dienes and trienes
Binns, Falmai,Hayes, Roy,Hodgetts, Kevin J.,Saengchantara, Suthiweth T.,Wallace, Timothy W.,Wallis, Christopher J.
, p. 3631 - 3658 (2007/10/03)
Thermal electrocyclic ring-opening of 4-alkyl-2-cyclobutene-1-carbaldehydes occurs at low temperature to give (2Z,4E)-alkadienals exclusively, and the process is exploited in transforming cis-3-cyclobutene-1,2-dimethanol 1 into a variety of naturally occurring 1,3,5-alkatrienes and 2,4-decadienoates. Desymmetrisation of 1 with Pseudomonas fluorescens lipase gives access to both enantiomers of 3-oxabicyclo[3.2.0]hept-6-en-2-one 4, for use in stereocontrolled routes to 6-oxygenated (2Z,4E)-alkadienals.
Synthesis of naturally occurring diene and trienes by Te/Li exchange on (1Z,3Z)-butyltelluro-4-methoxy-1,3-butadiene
Dabdoub, Miguel J.,Dabdoub, Vania B.,Baroni, Adriano C.M.,Hurtado, Gabriela R.,Barbosa, Sandro L.
experimental part, p. 1666 - 1670 (2010/05/19)
(1Z,3Z)-Butyltelluro-4-methoxy-1,3-butadiene 2 was obtained by the hydrotelluration of (Z)-1-methoxy-but-1-en-3-ynes 1. The butadienyllithium 3 obtained by the Te/Li exchange reaction in the (1Z,3Z)-1-butyltelluro-4-methoxy-1,3-butadiene 2 reacted with aldehydes to form the corresponding alcohols 4a-d with total retention of configuration. The alcohols formed undergo hydrolysis, resulting in the α,β,γ,δ-unsaturated aldehydes of (E,E) configuration, which are precursors of trienes obtained from natural sources. The products of this reaction were employed in the synthesis of methyl-(2E,4E)-decadienoate 7, which is a component of the flavor principles of ripe Bartlett pears. Performing the Wittig reaction of the methyl triphenylphosphorane with the deca-(2E,4E)-dienal 5a, we were able to synthesize the undeca-(1,3E,5E)-triene 6a. This compound is a sex-pheromone component of the marine brown algae Fucus serratus, Dictyopteris plagiograma, and Dictyopteris australis. Performing the Wittig reaction of methyl triphenylphosphorane with the octa-(2E,4E)-dienal 5c, the nona-(1,3E,5E)-triene 6b was synthesized. The compound obtained is a sex-pheromone component of the marine brown alga Sargassum horneri. The octa-(1,3E,5E)-triene 6c was easily obtained from hepta-(2E,4E)-dienal 5d by the Wittig reaction with methyl triphenylphophorane. This compound is a sex-pheromone component of the marine brown alga Fucus serratus.
Iron-catalyzed aerobic oxidation of allylic alcohols: The issue of C=C bond isomerization
Liu, Jinxian,Ma, Shengming
supporting information, p. 5150 - 5153 (2013/11/06)
An aerobic oxidation of allylic alcohols using Fe(NO3) 3·9H2O/TEMPO/NaCl as catalysts under atmospheric pressure of oxygen at room temperature was developed. This eco-friendly and mild protocol provides a convenient pathway to the synthesis of stereodefined α,β-unsaturated enals or enones with the retention of the C-C double-bond configuration.
(2E)-4,4-dimethoxy-2-butenal in the synthesis of conjugated dienes and dienals
Badanyan,Makaryan,Ovanesyan,Panosyan
, p. 633 - 639 (2007/10/03)
Using (2E)-4,4-dimethoxy-2-butenal as starting compound, methods were developed for synthesis of (2E,4E)-and (2E,4Z)-dimethoxyalkadienes. Deacetalization of the latter gives with high yield the corresponding dienals which are naturally occurring compounds and also synthons for preparation of conjugated dienes as key compounds for building up other natural products.
