Birch reduction synthesis

Tran orm-based or long-range strategies The retrosynthetic analysis is directed toward the application of powerful synthesis transforms. Functional groups are introduced into the target compound in order to establish the retion of a certain goal transform (e.g., the transform for the Diels-Alder reaction, Robinson annulation, Birch reduction, halolactonization, etc.). 

Birch Reductions reduction of aromatic rings Organic Reactions 1976, 23, 1. Tetrahedron 1986, 42, 6354. Cornprehensice Organic Synthesis 1991, voJ. 8, 107. 

Synthesis Since we can make both compounds from the same intermediate 395A, we ll use the Birch reduction route ... 

In polycyclic systems the Birch reduction of C—C double bonds is also highly stereoselective, e.g. in the synthesis of the thermodynamically favored trans-fused steroidal skeletons (see p. 104 and p. 278). 

Catalytic hydrogenation of the 14—15 double bond from the face opposite to the C18 substituent yields (196). Compound (196) contains the natural steroid stereochemistry around the D-ring. A metal-ammonia reduction of (196) forms the most stable product (197) thermodynamically. When R is equal to methyl, this process comprises an efficient total synthesis of estradiol methyl ester. Birch reduction of the A-ring of (197) followed by acid hydrolysis of the resultant enol ether allows access into the 19-norsteroids (198) (204). 

Dibenzothiophene, 1,2,3,4-tetrahydro-4-keto-synthesis, 4, 905 Dibenzothiophenes alkylation, 4, 724 Birch reduction, 4, 775 C NMR, 4, 11... 

Thiophene, 3-pentadeuterophenyl-chemical shifts, 4, 730 Thiophene, 2-phenyl-oxidation, 4, 800 phototranspositions, 4, 743 rearrangement, 4, 42 reduction, 4, 775 synthesis, 4, 865, 914 UV spectrum, 4, 735 Thiophene, 3-phenyl-photochemical rearrangements, 4, 735 phototranspositions, 4, 743 lsmeier formylation, 4, 759 Thiophene, 2-pivaloyl-Birch reduction, 4, 775 Thiophene, polybromo-reactivity, 4, 829 Thiophene, polylithio-synthesis, 4, 831 Thiophene, (propargylthio)-rearrangement, 4, 746 Thiophene, 2-(3-pyridinyl)-synthesis, 4, 781 Thiophene, 2-(5-pyrimidinyl)-synthesis, 4, 781 Thiophene, 3-pyrrolidinyl-cycloaddition reactions, 4, 68 with dimethyl acetylenedicarboxylate, 4, 788-789... 

The Y appendage of 2-cyclohexenone 191 cannot be directly disconnected by an alkylation transform. (y-Extended enolates derived from 2-cyclohexenones undergo alkylation a- rather than y- to the carbonyl group). However, 191 can be converted to 192 by application of the retro-Michael transform. The synthesis of 192 from methoxybenzene by way of the Birch reduction product 193 is straightforward. Another synthesis of 191 (free acid) is outlined in... 

The steroidal total synthesis intermediate (18) contains an aromatic ring of the type found in 5-methoxytetralin, a compound which undergoes Birch reduction slowly. As a consequence, compound (18) is reduced with... 

Reactions of 3- and 4-piperidone-derived enamines with a dienester gave intermediates which could be dehydrogenated to tetrahydroquinolines and tetrahydroisoquinolines (678). The methyl vinyl ketone annelation of pyrrolines was extended to an erythrinan synthesis (679). Perhydrophenan-threnones were obtained from 1-acetylcyclohexene and pyrrolidinocyclo-hexene (680) or alternatively from Birch reduction and cyclization of a 2-pyridyl ethyl ketone intermediate, which was formed by alkylation of an enamine with a 2-vinylpyridine (681). 

Asymmetric Birch reduction and reduction-alkylation in synthesis of natural products 99CC1263. 

Ketone (27) was needed for a synthesis of the boll weevil pheromone (28), Suggest a synthesis of (27) using Birch reduct ion,... 

Select one compound from (37) - (40) for synthesis by each of the methods of this chapter Robinson annelation, Diels-Alder reaction, total reduction of aromatics, and Birch reduction. 

Go, finally, (38) must be the Birch reduction product, derived from (44) via (45). This time base was used to move the double bond into conjugation. Synthesis ... 

The synthesis of longifolene in Scheme 13.30 commenced with a Birch reduction and tandem alkylation of methyl 2-methoxybenzoate (see Section 5.6.1.2). Step C is an intramolecular cycloaddition of a diazoalkane that is generated from an aziridinoimine intermediate. 

With an effective strategy for construction of the diazofluorene established, we set out to prepare the coupling partners required for synthesis of (—)-kinamycin F (6). The synthesis of the enone 117 began with meta-cresol (128, Scheme 3.23). Silylation formed the silyl ether 119 in nearly quantitative yield. Birch reduction of the silyl ether 119 formed the cyclohexadiene derivative 129 in excellent yield. Asymmetric dihydroxylation [52] of 129 occurred regioselectively to afford the... 

The first total synthesis of ( )-yohimbone (305) has been reported by Swan (769). Birch reduction of key intermediate 17-methoxyhexadehydroyohimbane (368), obtained from phenylhydrazine and 367, led to tetradehydroyohimbane derivative 369, which upon acid treatment gave yohimbenone (370). When 370... 

The second approach (224-226) employs O-methylhexadehydroyohimbine (420), prepared from spiroindeno-2-(l -tetrahydro-0-carboline)-l-onederivative 416 by photolysis and subsequent reduction, as the key intermediate. The side product (418) of the photolysis was also utilized for the preparation of 420 via subsequent phosphoryl chloride treatment and sodium borohydride reduction. Birch reduction of 420 resulted in enol ether 421, which could be transformed to 15,16-didehydroyohimbinone (410), prepared previously by Szantay et al. (74, 221) as a universal precursor of the synthesis of yohimbine-type alkaloids. 

In the actual synthesis, Birch reduction of anisole (10, R = CH3) affords the... 

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