A facile access to optically active ring C aromatic diterpene derivatives. Highly efficient synthesis of (+)-12-methyl-7-oxopodocarpa-8,11,13-triene-13-carboxylic acid and (+)-13-methyl-7-oxopodocarpa-8,11,13-triene-12-carboxylic acid from manool

A Concise Synthesis ofrac‐Ambrox®viathe Palladium(0)‐Catalyzed Carboalkoxylation of an Allylic Ammonium Salt, as Compared to a Formaldehyde HeteroDiels–AlderApproach

“…[85]. 23 conversion are increased in this later case. Quaternization may also be performed from the commercially available primary allylic amine 29c with either 3 molequiv.…”

“…[92] The chemical yield increased to 32 % when a 1 : 1 mixture of EtOH/THF was used. 25 Similarly, the monocyclofarnesyldiethylamine 30 also furnished the known ethyl ester 35b in 52 % yield as a 65 : 35 (E/Z) mixture (EtI, 0.01 mol-equiv. Pd (PPh 3 ) 4 , CO, 60 bar, EtOH, 60°C, 87 h).…”

“…Supplementary 13 C-NMR analytical data of the (Z)-stereoisomer: 173.0 (s); 139.3 (s); 132.0 (s); 123.9 (d); 116.4 (d); 51.7 (q); 33.6 (t); 32.2 (t); 26.3 (t); 25.7 (q); 23.4 (q); 17.6 (q). 25 When the reaction temperature is superior to 75°C, Hofmann elimination becomes a competing side reaction. The corresponding known Me esters 34d, [93][94][95][96][97] (80 : 20 (3E/3Z) mixture, were more efficiently obtained using 0.01 mol.-equiv of either Pd(PPh 3 ) 4 , or PdBr 2 /(CH 2 PoPy 2 ) 2 (MeOH/THF, CO, 60 bar, 60°C, 22 h, 52 -55 % yield, respectively, see Supplementary Material).…”

“…The simple conditions previously reported by Margot and Schlosser for the 'formal' hetero DielsÀ Alder reaction between paraformaldehyde and myrcene 1, [1][2][3][4] encouraged us to extend this reaction to other dienes, in particular, to the now readily available farnesene 2 [5][6][7][8] (Scheme 1), δ-pyronene 3 1[9-18] (Scheme 2), the known bicyclic diene 4, 2 [22][23][24][25][26][27][28][29][30][31][32] and 2,3-dimethylidenenorbornane 5, 3[35-39] as well as to the unreported diene 6 (Scheme 3). Our simple basic concept consisted of cleaving the resulting dihydropyran allylic CÀ O bond via a Birch reduction, [3,40] followed by cyclization of the correspond-ing homoallylic alcohol under acidic conditions, [41][42][43][44][45] in order to create new tetrahydrofuran derivatives, which might possess amber-like scents.…”

“…13 C-NMR: 200.8 (s); 136.6 (d); 136.2 (s); 128.0 (s); 127.7 (t); 40.4 (t); 39.8 (t); 35.1 (s); 32.8 (t); 28.5 (2q); 22.5 (t); 19.8 (q); 19.5 (t). MS: 206 (2, M + * ), 188 (18), 173 (20), 136 (27), 123 (27), 121 (100), 119 (22), 109 (10), 107 (23), 95 (28), 93 (65), 91 (24), 81 (29), 79 (32), 77(19), 69 (12), 67 (14), 55 (60), 41(25). Odorless.5-(2,6,6-Trimethylcyclohex-1-en-1-yl)pent-1-yn-3-one (23f).…”