A large number of complex indole-and indoline-containing alkaloids have been isolated from the natural products [
1-
4] and have become an area of intensive interest in synthetic organic chemistry [
5-
9]. Currently, C3-spirocyclization toward polycyclic indoles and indolines has been well studied [
10,
11]. And C2-spirocyclization of indolines is also occasionally reported although low reactivity at this position [
12-
15]. In addition, the construction of complex polycyclicindolines involving the C2-and C3-positions completed by a multistep reaction have also been well investigated (
Scheme 1a) [
16-
23]. Cycloaddition reaction is the most commonly used domino process to synthesize complex polycyclic indolines with the C2-and C3-positions participating in the transformation simultaneously (
Scheme 1b) [
24-
31]. Synthesis of polycyclic spiroindolines with oxa-and/or aza-tandem C2-and C3-cyclizations is relatively rare (
Scheme 1c) [
32-
34]. In 1999, Ciufolini
et al. [
34] reported a total synthesis that produced oxa-and aza-polycyclic spiro-fused indolines in the presence of BOP-Cl, Burgess reagent, and PhI(OAc)
2 starting from tryptophan analogs and (
S)-phenylalaninol (
Scheme 1d). They achieved five kinds of desired oxazine-containing spiro-fused cyclic structures
via four steps reactions, but no more than 50% yields were obtained in the final transformation even for adjust the substituents of the tryptophan analogs, lowering the overall yields. However, the highlight of the reaction is the nucleophilic N and O atom on the side chain expressing electrophilicity, and reacted simultaneously with both C2-and C3-position of indoles core in the final oxidative cyclization step. Another worthy-of-noting similar case is Dess−Martin periodinane-mediated cyclization reaction of unsaturated anilides by Nicolaou in 2002 [
35]. A plethora of phenoxazine-containing heterocycles are accessible in 0–57% yields by employing
γ,
δ-unsaturated amides, urethanes, or ureas as substrates
via an
o-imidoquinones species oxidized in site from the arylamide moiety. Despite these significant advances, important issues such as high yield, broad applicability, functional group tolerance, and process economy remain to be improved for the existing protocols [
24,
36,
37]. Thus, it remains challenging to efficiently synthesize oxazine-containing polycyclicindolines relevant to biological systems through cascade sequence with the C2-and C3-positions of the indole analogues participate in the transformation simultaneously.