Synthesis of (±) Peperomins

The total synthesis of natural antitumor agent (±) peperomin A, B and C are reported. These syntheses were started from benzophenones and diethyl succinate by Stobbe condensation. Three successive steps were employed to give the (±)-peperomins.     

Synthesis of (±)-penlanfuran

The title compound was efficiently synthesized from 3-furoic acid and 3-bromoanisole via the Birch reduction.     

Synthesis of (±)-Lsodeoxypodophyllotoxin

A process for the synthesis of (±)-isodeoxypodophyllotoxin starting from ethyl 3,4-methylcnedioxy-benzoacetate and methyl 3,4,5-trimethoxycinnamate is described.     

Total Synthesis of (±)-Patriscabrol and (±)-Boschnialactone

A total synthesis of (±)-patriscabrol (1) and (±)-boschnialactone (2) is described. The cyclopentapyranone skeleton is assembled by means of Baeyer-Villiger oxidation of ketol 5.     

Total Synthesis of (±)-Iridolactone

A total synthesis of (±)-iridolactone ( 1 ) from bicyclo[2.2.1]ketone 6 is described. Trisubstituted cyclopentenoid aldehyde 7 is a key intermediate.     

Total Synthesis of (±)-Barbatusol

The naturally occurring hypotensive agent barbatusol (1a) has been synthesized in racemic form from 3-isopropylveratrole and 4,4-dimethyl-2-cyclohexene-1-one. An improved procedure for deprotection of barbatusol dimethyl ether (1b) is described.     

Total Synthesis of (±)-Gelsemine

A complex molecular reorganization ( 1 → 2 ), a sequential anionic aza-Cope rearrangement and Mannich cyclization, and an unprecedented intramolecular Heck reaction of the tetrasubstituted double bond of a vinylogous carbamate are key steps in a new total synthesis of (±)-gelsemine ( 3 ). MOM=methoxymethyl, DBU=1,8-diazabicyclo[5.4.0]undec-7-ene.     

Synthesis of (±)-methylenolactocin and (±)-trans cognac lactone

The title compounds were efficeintly synthesized from 3-fuancarboxylic acid via the Birch recuction-elimination.     

Synthesis of (±)-latifolin dimethyl ether

(±)-Latifolin dimethyl ether has been synthesized by coupling 1,2,4-trimethoxybenzene and o-methoxycinnamyl cation. The isomeric benzylstyrene is also a product of the reaction. Among the possible biogenetic routes for the related compounds present in Dalbergia latifolia the most likely steps seem to be phenylcinnamic esters and 4-phenylcoumarins followed by stages of reduction. The alternative of cinnamyl cation functioning will limit the biosynthesis only to latifolin type of compounds.     

Synthesis of 28,29-bisnor-(±)-kijanolide

0(26)-Methyl-28,29-bisnor-(±)-kijanolide (23) has been synthesized via aldol reaction of spirotetronate 3 with octahydronaphthalene aldehyde 4 and subsequent macrocyclization of the resulting product.     

A Short Synthesis of (±)-Muscone

(±)-Muscone ((±)-1) has been synthesised in three steps from 2-(2′-methylprop-2′-enyl)cyclododecan-1-one ( 2 ). The synthesis involves two key transformations: a Lewis-acid-mediated intramolecular ene reaction ( 2→3 ) and the β-cleavage of the bicyclic potassium alkoxide 3a′ to the macrocyclic enone (Z)- 11 .     

The Total Synthesis of (±)-Camphor and (±)-Epicamphorenone from Methylcyclopentadiene

The total synthesis of (±)-carnphor and (±)-epicamphorenone from methylcyclopentadiene are described.     

Total Synthesis of (±)-2-Pupukeanone

(±)-2-Pupukenone ( 4 ) has been synthesized, the key step being the intramolcular Diels-Alder reaction of the intermediate 13 to 14 (42%) and 15 (14%). The bromodiene 12 has been obtained from the reaction of α-isopropylidene-γ-lactone (Scheme 2) 12 with sodium phenylselenide and subsequent esterification to 9 , oxidation and thermal elimination of which furnished 10 . Reduction of 10 with diisobutylaluminimum hydride and treatment of the resulting alcohol 11 with PBr₃ led to the required bromodiene 12 . Finally, hydrogenation of the 14 on Pt(C) in CH₃OH gave a 4:1 mixture of 2-pupukeanone ( 4 ) and epi-2-pupukeanone 16 .     

Synthesis of (±)-O-methylcannabichromene and some homologues

A facile novel synthesis of (±)-O-methylcannabichromene ( 5d ) together with (±)-2-methyl-2-(4-methyl-3-pentenyl)-5-methoxy-2H-benzopyran ( 5a ) and its 7-methyl ( 5b ) and 7-propyl ( 5c ) homologues, using organolithium salts is described.