Syntheses of the (-)-.alpha.-and (+)-.beta.-cis-bergamotenes

Abstract

Kende for a gift of the methyl ester of 1,2-dipropylcyclopropene-3carboxylic acid. chlorate in 25 ml of anhydrous ether was treated with a solution of 0.0368 g (0.965 mmol) of lithium aluminum hydride in 10 ml of ether. The reaction was stirred 0.5 hr under nitrogen at room temperature, cooled in an ice bath, and hydrolyzed by dropwise addition of water. The crude reaction product was filtered, diluted with two 25-ml portions of ether, and dried over magnesium sulfate.Removal of ether afforded a viscous oil which was subjected to Kragen tube distillation (oil bath temperature 80-120" (8 mm)). The product was identified as 1,2,3-tri-t-butylcyclopropene (8) from the following data: infrared spectrum: v::: (cm-1) 2960 (s), 2900 (m), 2865 (m), 1835 (w), 1475 (m), 1465 (m), 1395 (m), 1365 (m), 1355 (w), and 1275 (w); mass spectrum: m/e 208, 207, and 151; nmr spectrum: 0. 82 (9 H, s), 1.16 (18 H, s) 1.37, (1 H, s). An acceptable analysis could not be obtained for this compound. 168 Anal. Calcd for C16H~s: C, 86.46; H, 13.54. Found: C, 85.66; H, 13.57. Reaction of Cation 5d with r-Butyllithium. A suspension of 0.0962 g (0.314 mmol) of tri-t-butylcyclopropenyl perchlorate in 25 ml of anhydrous benzene was prepared under nitrogen and quenched The Syntheses of the ( -)-CY-and ( +)-P-cis-Bergamotenes'Abstract: Syntheses of (-)-a-cis-bergamotene (2) a n d (+)-0-cis-bergamotene (3) from (-)+-pinene are described, The isomer 2 was shown to be identical with a sesquiterpene hydrocarbon isolated from oils of opoponax (Commiphora erythraea var. glabrescens Engler) a n d black pepper (Piper nigrum L.). T h e isomer 3 was found t o be different from an isolate of Indian valerian oil (Valeriana wallichi) which has been assigned this structure.he structure 1 has been proposed for a sesquiterpene Mr. Wenninger for his generosity in providing us with samples of acis-, a-trans-, and P-trans-bergamotenes.

Exploration of the versatility of ring opening metathesis polymerization: an approach for gaining access to low density polymeric aerogels

“…The synthesis of the iodo-norbornene monomers was accomplished by initially tosylating the corresponding norbornene alcohol 3 in the presence of 4-(dimethylamino)pyridine (DMAP) followed by tosyl displacement using sodium iodide (Scheme 1c). [19][20][21] As a practical way to double the number of chemical functionalities in one monomer, 5-norbornene-2,3-dimethanol 10 was used to prepare bis-tosylated norbornene monomer 11 and bisiodo-norbornene monomer 12 as a typical example of functional monomers for monitoring of gel formation. Full details of the synthesis and characterization of norbornene-based monomers are described in the Supporting Information.…”

Stereoselective Synthesis of Bicyclo[3.1.1]Heptane Derivatives via Intramolecular Photocycloaddition Reaction

“…We reported an N-ylide [2,3]-and [3,3] As outlined in Scheme 1, hypochlorous acid, generated in situ from calcium hypochlorite and CO 2 , reacted with (R)-(-)-linalool (4) to provide allylic chloride, which was treated with dimethylamine in aqueous EtOH at room temper ature to give the correspondin g allylamine 5 via regioselectiv e S N 2 reaction. Reaction of 5 with ethyl bromoacetate in EtOH pr ovided quaternary ammonium salt 6 in a quantitative yield.…”

“…Several synthetic procedures of its representative hydrocarbon counterparts 2 and 3 have been reported. endo--Bergamotene (2) has been pr epared by Gibson and Erman in 12 steps starting from -pinene [2]. Corey, Cane and Libit have prepared exo--bergamotene (3) using a photo chemical [2+2] cycloaddition of 1,5-d iene in 21 steps fro m geranyl acetate [3].…”

“…Corey, Cane and Libit have prepared exo--bergamotene (3) using a photo chemical [2+2] cycloaddition of 1,5-d iene in 21 steps fro m geranyl acetate [3]. Larsen and Monti have prepared endo--bergamotene (2) and exo-isomer 3 using intramolecular ring closure for the formation of the cyclobutane ring in 13 steps [4] . Although the d irect construction of the acid-labile 2-methylbicyclo[3.1.1]hept-2-ene skeleton and the unambiguous stereocontrol of the quaternary C-6 carbon center h ave only been partially achieved by these earlier endeavors, these methods do not perm it the accu mulation of larg e amounts of mat erial owing to ma ny complicated steps and lo w overall yields.…”

Chemistry Around Pinene and Pinane: A Facile Synthesis of Cyclobutanes and Oxatricyclo‐Derivative of Pinane from cis‐ and trans‐Pinanols

“…Ether 12 has been previously synthesized by several research groups as an intermediate for C(9)-functionalized fenchenes [19], pinenes [20] including cis-bergamotenes [21] and Boll Weevil pheromone grandisol [22]. However, the methods for obtaining ether 12 described in [19 -22] do not appear very practical because they employ oxidation of trans-pinanol with such reagents as elemental Br 2 and double-to-quadruple weight excess of yellow mercury oxide in combination with UV irradiation.…”