Caparrapi oxide

R)- and (S)-LBA 52 were also applied to the diastereoselective cychzafion of optically acttve hydroxypolyprenoid 53 to afford after several steps the natural bicyclic sesquiterpene ethers (-)-caparrapi oxide and (-i-)-8-epicaparrapi oxide, respectively (Scheme 5.69) [130]. Notably, LBAs 52 and ent-52 were able to... 

Syntheses have been reported for several other natural products related structurally to carotenoids, viz. dihydroactinidiolide (123) and tetrahydroactinidiolide (124), trans- and cis-a-damascone (125), dihydroedulans I and II, (51) and (52), bicyclodamascenones A and B, (53) and (54), the diastereoisomeric caparrapi oxides (126), ( )-a-chamigrene (127), and the novel passion-fruit ionone derivatives (47) and (48). ... 

Full details of the structural determination of nigakialcohol (24) have been published. Co-occurring with aplysistatin (25) in Laurencia cf. palisada Yamada are the marine sesquiterpenoids palisadin A (26) and B (27), 5-acetoxypalisadin B (28), 12-hydroxypalisadin B (29), and palisol (30). 3/3-Bromo-8-epi-caparrapi oxide (32) has been synthesized by a procedure which... 

Caparrapi balsam is a fragant oil from Colombia which is stated to be of some therapeutic value 18), A bicyclic ether (210) 18,59,93) called caparrapi oxide was isolated as the main component (up to 43%) from this oil. Whereas the natural product (210) is virtually odorless, its diastereoisomer (211) has pronounced amber-like odor properties 455). 

Brooks C J W, Campbell M M 1969 Caparrapi oxide, a sesquiterpenoid from caparrapi oil. Phytochemistry 8 215-218... 

The reaction of nerolidol (144) with 2,4,4,6-tetrabromocycIohexa-2,5-dione results in brominative cyclization in a biomimetic fashion, to furnish a- and /3-snyderols (145a) and (145b) and 3-bromo-caparrapi oxide (146) and its... 

SCHEME 9.49 Total syntheses of (-)-caparrapi oxide 43, (+)-caparrapi oxide 43, (+)-8-epicapparapi oxide 44, and (+)-dysifragin 45. 

Subsequent study revealed that the chiral LBA (16) canbeusedas artificial cyclases for the asymmetric syntheses of (-)-caparrapi oxide (17) and (+)-8-epicaparrapi oxide (18) [28a,b]. (17) and (18) can be diastereoselectively synthesized from (S)-(19) (prepared in three steps from commercially available famesol) by reagent control of (R)-16 and (S)-16, respectively, regardless of the chirality of (S)-19 (Scheme 1.25). 

These strategies were successfully applied to the asymmetric total synthesis of (—)-caparrapi oxide and (- -)-8-epicaparrapi oxide, acid-sensitive natural compounds, starting from famesol [47]. The key asymmetric cyclizations were achieved with high enantio- and diastereoseledivities produdng the desired compounds in good yields as shown in Scheme 10.25. 

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