Farnesol synthesis

Unsymmetrical trans vinyl halides have been prepared from acetylenic alcohols by Corey and co-workers (as illustrated in the accompanying formulation) in connection with their synthesis of farnesol and Gecropia juvenile hormone. Several syntheses of vinyl halides (with... 

Stereospecific Synthesis of Trisubstituted Olefins from Acetylenes or Aldehydes Applications to the Total Synthesis of Cecropia Juvenile Hormones (JH) and Farnesol... 

The intramolecular Hiyama reaction is excellently suited for the construction of carbocyclic and heterocyclic ring systems of different size. In most examples, problems of induced diastereoselectivity are involved (Sections 1.3.3.3.9.2.2. and D.2.3.). In the total synthesis of the antitumor germacranolide ( )-costunolide from ( ,.E)-farnesol, the correctly substituted ( , )-cyclodecadiene moiety was constructed by an intramolecular Hiyama reaction22. 

The jS-oxido-ylides synthesis of trisubstituted olefins has also been applied to the synthesis of farnesol (127). The phosphonium salt (123) with the aldehyde (124) and formaldehyde gave the hydroxy farnesol derivative (125) which was transformed into farnesol (127) and into (126), a position isomer of Cj juvenile hormone. 

Terpenes important for both fragrances and flavours can be prepared from citral, such as citronellol, linalool, nerolidol, geraniol, farnesol and bisabolol. Citral is also an important starting material for the synthesis of vitamins A and E, carotenoids and other flavour and fragrance compounds like ionones. Most of the /3-ionone synthesised is probably used for vitamin A synthesis. 

Yields of chlorides are good to excellent for primary and secondary alcohols, but a competing olefin-forming elimination process renders the method of limited value for preparing tertiary chlorides.12 An adaptation of the procedure using carbon tetrabromide allows the synthesis of alkyl bromides. Some examples are the preparation of w-C5H1 IBr (97%) and C H5CH2Br (96%).12 Famesyl bromide has been prepared in 90% yield from farnesol.23... 

Boron trifluoride etherate promotes the fWt/a-selcctivc oxacyclization of polyepoxides derived from various acyclic terpenoid polyalkenes, including geraniol, farnesol, and geranylgeraniol, providing an efficient and stereoselective synthesis of substituted oxepanes and fused polyoxepanes. The oxacyclization transformations may mimic ringforming steps in the biosynthesis of trans-syn-trans-fused polycyclic ether marine natural products <2002JOC2515>. 

The metal derivatives of alkynes can be added to carbonyl electrophiles as in the following examples. The first (we have reminded you of the mechanism for this) is the initial step of an important synthesis of the antibiotic, erythronolide A, and the second is the penultimate step of a synthesis of the widespread natural product, farnesol. 

Of the best-known insect orders, only the Hemiptera, the true bugs, stand out as a group without a clearly recognized JH. An early report identified JH I as the principal hormone in the hemolymph of the adult female bean beetle, Riptortus clavatus (Hemiptera Alydidae) by gas chromatography—MS (GC—MS).78 It was reported that, of the three compounds JH I, II, and III, JH I was the most effective for inducing yolk protein synthesis in diapausing adults of this species.78 More recently, it has been reported that a compound close to JH III, but not JH III, is the hormone in the two spotted stink bug Perillus bioculatus (Hemiptera Pentatomidae). Production of this hormone is stimulated by farnesol, a known precursor of JH III.79... 

Then Li et al. reported on a concise total synthesis of ( )-sarcophytol A (3) from the derivative of , -farnesol (91) by a low-valent titanium-mediated intramolecular McMurry olefination strategy (Scheme 6-4). ... 

Mechelke, M.F., and Wiemer, D.F. (1999). Synthesis of farnesol analogues through Cu(I)-mediated displacements of allylic THP ethers by grignard reagents. J Org Chem 64 4821 829. 

A method has been described for the functionalization of the isopropylidene terminus of isoprenoids. For example, geranyl benzyl ether (208) was converted into the phenyl thioether (210) by treatment with PhSCl and elimination of HCl. Oxidation and reaction with trimethyl phosphite gave the primary alcohol (209) stereospecifically in 75% overall yield. Use has been made of this procedure in the synthesis of solanesol (C45) from three C15 units.The tosyl derivative of the hydroxylated farnesol (211) reacts with the bromide (212) prepared from (213) to give the C30 product (215), the bromide (216) of which, after further reaction with (214), affords the solanesol derivative (217) and thence solanesol (205). 

Another molecule involved in the high-to-low ceU density transition identified in C. albicans is tyrosol (42). As opposed to farnesol, it promotes cell growth and the development of germ tubes at low cell densities. Expression profiling of cultures under conditions of reduced tyrosol concentration showed reduced expression of proteins involved in DNA synthesis and ceU cycle regulation (43). Other putative C. albicans quorum sensing molecules include the substance MARS of unknown identity and, with diminutive effect, farsenoic acid (41). 

The relative stereochemistry of the substituents attached to the cyclopropane ring of presqualene alcohol received further confirmation by a synthesis of the triacetate (13), obtainable from (1) by ozonolysis, reduction, and acetylation. Treatment of 3-methyl-truns-hex-2-ene-l,6-diacetate (14) with ethyl diazoacetate in the presence of copper powder gave two isomers (15) and (16) whose stereochemistry was assigned by n.m.r. The triacetate derived from synthetic (15) by reduction and acetylation was identical in all respects with the triacetate (13) from natural presqualene alcohol. Presqualene alcohol has a c.d. curve similar to, but of opposite sign to, that of (li ,2i )-trans-chrysanthemyl alcohol (17). The mechanism for the stereospecific biosynthesis of squalene from farnesol via presqualene alcohol has received detailed comment. ... 

Another forefront technique to improve the function of the stratum corneum and enhance barrier repair in dry skin is the use of epidermal differentiation. A number of hormone receptors for epidermal differentiation have been identified. This family of receptors includes retinoic acid receptors, the steroid receptors, the thyroid receptors, the Vitamin D receptors, the peroxisome proliferator-activated receptors, the farnesol-activated receptors, and the liver-activated receptors. It is reported that these transcription factors bind their respective ligands and regulate many of the aspects of cellular proliferation and differentiation. Examples of ligands for the last three transcription factors are fatty acids for the peroxisome proliferator-activated receptor, famesol for the farnesol-activated receptor, and hydroxylated cholesterol derivatives for the liver-activated receptor. The stimulation of epidermal differentiation stimulated the synthesis of involucrin, filaggrin, and the enzymes of the ceramide synthesis pathway (74). 

C-F-IMF, 170, containing farnesyl moiety labelled with has been obtained involving the synthesis of " C-labelled farnesol [ " C-F, 173] from ketone 174 (equation 60), 169 and 170 have been synthesized in order to clear the pharmacokinetic profile of these drugs in vivo and in vitro. 

The efficiency of the above one-pot methylalumination procedure applied to the synthesis of tran.s -farnesol compares favorably with the reported three-step procedure involving preparation of the propargylic alcohol, L1A1H4 reduction of the triple bond, iodination of the vinyl carbon-aluminum bond, and final coupling of the alkenyl iodide with lithium dimethylcuprate. " ... 

Studies toward the biomimetic total synthesis of (+)-chatancin were conducted by P. Deslongchamps et al. The authors planned to use a transannular Diels-Alder reaction of a pyranophane intermediate as the key ring forming step. The cyclic dienedione precursor for this transformation was prepared using the Prins reaction on a substrate derived from trans-trans farnesol. 

This compound must arise from bromonium ion cyclization of the 6,7-bromohydrin of farnesol acetate. Hydrolysis of the acetate group in (47) and sequential treatment with phosphorus tribromide and water gave obtusenol (46). Other syntheses of marine sesquiterpenoids include those of pallescensin-E (48),30 furoventalene (49),81 and dactyloxene-B (50) and -C (51).32 The last mentioned established the absolute configurations of the two dactyloxenes. A second synthesis of ancistrofuran (53) and its C-2 epimer has been recorded starting from the lactone (52) which is derived from homogeranic acid (Scheme 3).33... 

Intramolecular diazo olefin cyclization. Corey and Achiwa1 have-described a simple four-step synthesis of scsquicarcne (5) from oi.v-tron.s-farnesol (l),2 in which the key step is an intramolecular addition reaction of an unsaturated diazo... 

Total synthesis of a-santalol.2 a-Santalol (7) has been synthesized from (—)-ir-bromotricyclene (1) by essentially the same procedure used previously by Corey and Kirst for the synthesis of trans,frans-farnesol (2, 240-241). The starting material was converted into the terminal acetylene (2) by reaction with lithio-1-trimethylsilylpropyne followed by desilylation (2, 239-240). This was converted into the propargylic alcohol (3) by way of the lithium derivative by reaction with paraformaldehyde. /run.v-Hydroaluruination was then effected by treatment with H-buty(lithium followed by diisobutylaluminum hydride. Treatment with iodine... 

In obtaining all-tram bis-homo-farnesol (7), needed for the synthesis of Cig-JH, Still and co-workers (1979) made use of their former finding (Still and Mitra, 1978) on the [2,3]-sigmatropic rearrangement of alkoxyorganolithium reagents, which provides an efficient method for the preparation of Z-homoallylic alcohols. 

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